God has spoken to us by His Son

Numbers 36:13 (ESV)
These are the commandments and the rules that the LORD commanded through Moses to the people of Israel in the plains of Moab by the Jordan at Jericho.

That the LORD commanded through Moses to the people of Israel. Moses was the mouthpiece of God through which He proclaimed His commandments and rules to the people of Israel. God spoke through Moses. God speaks through people. It is not because of God's weakness or inability that He speaks through human beings to deliver His message. God CAN speak directly to us, as He did when He declared the Ten Commandments by His own voice out of the fire:
Deuteronomy 5:22-26 (ESV)
"These words the LORD spoke to all your assembly at the mountain out of the midst of the fire, the cloud, and the thick darkness, with a loud voice; and he added no more. And he wrote them on two tablets of stone and gave them to me. [23] And as soon as you heard the voice out of the midst of the darkness, while the mountain was burning with fire, you came near to me, all the heads of your tribes, and your elders. [24] And you said, ''Behold, the LORD our God has shown us his glory and greatness, and we have heard his voice out of the midst of the fire. This day we have seen God speak with man, and man still live. [25] Now therefore why should we die? For this great fire will consume us. If we hear the voice of the LORD our God any more, we shall die. For who is there of all flesh, that has heard the voice of the living God speaking out of the midst of fire as we have, and has still lived?

We see then from the above passage that God does not speak to us directly because of OUR weakness, not His. God is perfectly holy God, whose holiness not even sinless angels dare not look, lest THEY die:
Isaiah 6:2-3 (KJV)
Above it stood the seraphims: each one had six wings; with twain he covered his face, and with twain he covered his feet, and with twain he did fly. [3] And one cried unto another, and said, Holy, holy, holy, is the Lord of hosts: the whole earth is full of his glory.
How then can we corruptible humans, defiled with sinful thoughts, words and deeds, expect to live when we hear the holy voice of God? We can understand why Israelites practically begged Moses that God would not talk to them directly. They could not stand before the blazing furnace that was God's Word. Their hearts melted like wax before His holiness, His Law exposing their iniquity like a bright light and making them condemned before Him. Through the fire they saw a glimpse of God's burning wrath in Hell, and through His pronouncement a preview of the Judgment Day. They compared their own sinfulness to His commandments, and saw how far they have fallen from the glory of God, and how much they deserved to die. They could not lift their eyes to heaven, and cried in their hearts like the tax collector:
Luke 18:13 (ESV)
But the tax collector, standing far off, would not even lift up his eyes to heaven, but beat his breast, saying, ''God, be merciful to me, a sinner!''

It is then for our safety that God speaks through people, lest we be consumed by His power of His holiness. For read what He says when Israel pleads that God speak through Moses:
Deuteronomy 5:27-29 (ESV)
Go near and hear all that the LORD our God will say and speak to us all that the LORD our God will speak to you, and we will hear and do it.'' [28] "And the LORD heard your words, when you spoke to me. And the LORD said to me, ''I have heard the words of this people, which they have spoken to you. They are right in all that they have spoken. [29] Oh that they had such a mind as this always, to fear me and to keep all my commandments, that it might go well with them and with their descendants forever!
God says, They are right in all they have spoken. They were right in their fear of God. They were correct that if God continue to speak to them, they would die. They were right that a man must speak for them as prophet, lest God's wrath consume them all. So then, a prophet's mouth works as a softening filter for God's words to be heard. This is why we need faith when we are reading the Bible or listening to preachers. Though the Bible was written through men, and though it is only a human in the pulpit, we need faith to believe that it is God Himself speaking through these means, lest we die by His holiness. We must have fear of God in our hearts always when we listen to the Word being preached. We must not look at the outer appearance, but listen to what God almighty is saying to us through His vessels. See how God says in above verse that, when we have this fear always, it will go well with them and our descendants. We need a fear before God's voice, even if it is being spoken from weak vessels. When we read the Holy Bible, we must reject the idea that it was written by men, but listen to the holy and powerful voice of the Holy Spirit who wrote this book through men, for our own sake.

Another reason why God spoke through Moses to the people of Israel was because Moses was a child of Israel. People of Israel can relate to Moses, because he is one of them. Moses was one of the brethren, a man from the tribe of Levite. Moses understood the pain of his people. He himself as a baby survived the killing of all the firstborn sons. Though he did not experience slavery like his brethren, he saw their sorrow and their burdens, and desired to free them. He suffered 40 years of persecution from Pharaoh, having gone in exile. This man knew them, and had shared in the pain with them. And because it was this Moses speaking, people of Israel were willing to listen. Thus Moses was a fitting mouthpiece of God, because he was one of them.

We see then this is also because of our weakness, the tendency to reject that which is unfamiliar, that God speaks to us through man. God is Spirit, but we are of the flesh. God is therefore unfamiliar to us. He is not one of us, nor is He like us, as our sinful minds are so prone to imagine:
Psalm 50:21 (ESV)
These things you have done, and I have been silent; you thought that I was one like yourself. But now I rebuke you and lay the charge before you.
God is foreign to us. Our small minds cannot contain His fullness. We only collect bits of Him that we like, and most of the time reduce Him down to some imagination that resembles something out of the paintings of Michaelangelo. But that is not God at all. God is not like anything or anyone. He is all by Himself. That is why His name is I AM THAT I AM. Who can compare with God? He alone dwells in the light that no one can approach.

It was therefore fitting that God speak through man to man, so we can understand His words. It is similar to the work of translation from one language to another. God speaks spiritual language, but we are carnal, meaning we don't speak the same language as God. We only think and speak about the things of man. As with language interpretation, we need someone in between who knows both and understand both languages to help us. For how can we understand God's word unless someone explains to us?:
Acts 8:30-35 (KJV)
And Philip ran thither to him , and heard him read the prophet Esaias, and said, Understandest thou what thou readest? [31] And he said, How can I, except some man should guide me? And he desired Philip that he would come up and sit with him. [32] The place of the scripture which he read was this, He was led as a sheep to the slaughter; and like a lamb dumb before his shearer, so opened he not his mouth: [33] In his humiliation his judgment was taken away: and who shall declare his generation? for his life is taken from the earth. [34] And the eunuch answered Philip, and said, I pray thee, of whom speaketh the prophet this? of himself, or of some other man? [35] Then Philip opened his mouth, and began at the same scripture, and preached unto him Jesus.

God had anointed Philip with the Holy Spirit and made him a prophet of God, that he may first understand God's word. And because Philip was an eyewitness to the crucifixion of Jesus, he could explain more than anyone what the text meant to this eunuch. But no good interpreter is one who does not know both languages. Philip was well acquainted with the language of unbelief. It was Philip who spoke so unbelievingly of Christ's power when Christ tested him at the feeding of 5000. It was this Philip that doubted that Jesus was God:
John 14:8-10 (KJV)
Philip saith unto him, Lord, shew us the Father, and it sufficeth us. [9] Jesus saith unto him, Have I been so long time with you, and yet hast thou not known me, Philip? he that hath seen me hath seen the Father; and how sayest thou then , Shew us the Father? [10] Believest thou not that I am in the Father, and the Father in me? the words that I speak unto you I speak not of myself: but the Father that dwelleth in me, he doeth the works.
But when he saw Christ die and rise again, and the Holy Spirit came and reminded him of all things that Christ did in fulfillment of the scriptures, he was now fit to be the interpreter of God's language. He was fit also because he understood the unbelievers' heart. He used to be an unbeliever. He could relate with them, and they could relate with him. How much do we need people like him to be mouthpieces of God, people who have personally and intimately seen the glory of the Father in Christ Jesus, and who is humble enough to sympathize with and have compassion on the unbelievers?

But who is the greatest Teacher who explained all things to us? It is Jesus Christ, the Son of God. He was the great Interpreter that came down from Heaven to tell us of the things of God. No man has ever seen God, but He that was in the bosom of the Father, God has declared Him to the world. No man has ever ascended to heaven and has come back to tell us what God is like. All who ever went up to heaven never came back alive. But Christ has come down to us as the only Messenger from eternity, to testify to us of the goodness of heaven and of the horrors of hell. He came to tell us of the mysteries of Kingdom of God. And what better Interpreter of the things of God than God Himself? Christ was God manifest in the flesh, so that God could explain to us what He means. No man ever spoke like Jesus Christ, because it was God Himself speaking through Christ. God was no longer content with sending human prophets, so He sent His own Self, His Beloved and only begotten Son, into the world, to explain to man fully of the things of the Sprit of God. So if God Himself came down to speak His truth to us, what other teachers do we need to hear? We do well to hear the voice of Jesus Christ, and reject a thousand inferior voices, for in listening to Him, we listen to the very voice of God the Creator.

Christ is our best Teacher of the things of God not only because He is God, but He is also man. Like Moses, He is one of us. He suffered, He wept, He got tired, He hungered, He worked - He was tempted in every point, yet without sin. We can relate to Him, and He can relate to us. He knows all our pain, because He has gone through same for us. And because He was man, He could speak the things of God comfortably to us, not as though fire that we cannot bear to hear Him. When we listen to God through Christ, we can have the fear of God in us, yet at the same time feel not distant from God, but be joyful that God is with us in Jesus. Christ was the Prophet that God promised He would raise up from among us:
Deuteronomy 18:18 (ESV)
I will raise up for them a prophet like you from among their brothers. And I will put my words in his mouth, and he shall speak to them all that I command him.

And because He was a man, He could speak to us the things of God in terms that we could understand. Imagine a university professor trying to explain quantum physics to a 6 year old child. He would simplify the content as much as possible, and use anecdotes and illustrations that a 6 year old can understand. He would speak to them as a child, that the child might understand it. This is what Christ did when He came as a man spoke to us in parables. He spoke to us in an earthly way, so that we may be able to get our minds around the heavenly:
Mark 4:30 (ESV)
And he said, "With what can we compare the kingdom of God, or what parable shall we use for it?
John 3:12 (ESV)
If I have told you earthly things and you do not believe, how can you believe if I tell you heavenly things?

However, just as not all 6 year olds will understand quantum physics even if the professor presents the clearest and the easiest explanation, not all can understand Jesus. The things of the Spirit of God are foolishness to fleshly minds, even if it comes in the easiest forms. How easy are the parables of Christ? We teach them to little kids in Sunday School. Yet the most sophisticated adults minds have trouble understanding what it means. It is because God has not given them ears to hear:
Matthew 13:11-16 (KJV)
He answered and said unto them, Because it is given unto you to know the mysteries of the kingdom of heaven, but to them it is not given. [12] For whosoever hath, to him shall be given, and he shall have more abundance: but whosoever hath not, from him shall be taken away even that he hath. [13] Therefore speak I to them in parables: because they seeing see not; and hearing they hear not, neither do they understand. [14] And in them is fulfilled the prophecy of Esaias, which saith, By hearing ye shall hear, and shall not understand; and seeing ye shall see, and shall not perceive: [15] For this people's heart is waxed gross, and their ears are dull of hearing, and their eyes they have closed; lest at any time they should see with their eyes, and hear with their ears, and should understand with their heart, and should be converted, and I should heal them. [16] But blessed are your eyes, for they see: and your ears, for they hear.

Only those who are given blessed ears, eyes and heart can hear and understand what Christ means. GOD must enable a person to understand what Christ is saying. There must be a supernatural transformation of the mind. The carnal mind must be changed into a spiritual mind. The Holy Spirit must come, and give us the mind of Christ, in order that we may understand Him as He meant it. Only then is it possible for a human being to understand the mysteries of the Kingdom of God. Unlike the professor, the problem that God must deal with sinners is not merely difficulty, but impossibility. Human beings are not just immature or foolish or weak, but they are altogether DEAD to God. It is not possible that they can know God or understand Him, as much as a dead corpse has no chance of learning anything. They need to be made alive. The Holy Spirit must breathe life into the mind and give it the ability to understand God. It takes nothing short of a miracle:
John 3:3 (ESV)
Jesus answered him, "Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God."
1 Corinthians 2:14-16 (ESV)
The natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned. [15] The spiritual person judges all things, but is himself to be judged by no one. [16] "For who has understood the mind of the Lord so as to instruct him?" But we have the mind of Christ.

Because of our total inability to know His thoughts through our wisdom, God simply makes us to have His thoughts by His Spirit. It is as though the professor, having failed in all other means, transplants his own mind inside the 6 year old, that the kid may have the thoughts of the professor, and understand exactly the things the professor was trying to teach him. Regeneration is like this, but is infinitely more than this. God has given His own mind to us through the Holy Spirit, that we may know Him and understand Him. So then, when we receive a great understanding or idea of the things of God, let us not to boast, but thank Him for giving his mind to us:
1 Corinthians 2:11-12 (ESV)
For who knows a person's thoughts except the spirit of that person, which is in him? So also no one comprehends the thoughts of God except the Spirit of God. [12] Now we have received not the spirit of the world, but the Spirit who is from God, that we might understand the things freely given us by God.

Through the Holy Spirit, not only do all believers understand the things of God, they can also all be mouthpieces through which God can speak to sinners. Remember when Moses said to Joshua, when the 70 elders of Israel received the Spirit and began prophesying:
Numbers 11:29 (ESV)
But Moses said to him, "Are you jealous for my sake? Would that all the LORD's people were prophets, that the LORD would put his Spirit on them!"
Joshua thought that only Moses should be the one prophesying, but Moses on the other hand desired that all God's people were prophets like him. This is also Jesus Christ's heart for us. Christ desires that all His people were like him, anointed with the Spirit, and preaching the truth of God to the lost. And this desire He fulfilled when He sent Holy Spirit on Pentecost to His people:
Acts 2:32-34,38-39 (KJV)
This Jesus hath God raised up, whereof we all are witnesses. [33] Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, he hath shed forth this, which ye now see and hear. [34] For David is not ascended into the heavens: but he saith himself, The Lord said unto my Lord, Sit thou on my right hand, [38] Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost. [39] For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call.

We, who have received the Holy Spirit from on high, must therefore preach the Gospel. The time is short until the harvest, but the labourers are few. The night is coming, when no man can work. We must pray, that the Holy Spirit send us, and that we may be mouths for Christ, as Aaron was to Moses, and as Moses was to God. How long shall we tarry, and tip toe around the Gospel of Jesus Christ, and speak not directly the truth that can set people free from their sins? We can't but speak what we have heard and have seen. As we have believed, we shall speak. Lord Jesus, grant us the boldness to speak your word without fear. Speak through us, and burst forth through through our closed lips and cowardice as Your Spirit has done on Pentecost.

Let us cry out to Lord to send us forth, as Isaiah did. Isaiah confessed of having a dirty mouth when he first saw the Lord's glory:
Isaiah 6:5 (KJV)
Then said I, Woe is me! for I am undone; because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips: for mine eyes have seen the King, the Lord of hosts.
But after having his mouth cleansed by the Holy Spirit fire, he desired the Lord that He send him to be a prophet:
Isaiah 6:8-9 (KJV)
Also I heard the voice of the Lord, saying, Whom shall I send, and who will go for us? Then said I, Here am I; send me. [9] And he said, Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not.
Let us have such boldness. Is our sin stopping us from becoming His prophet? Let us confess them and repent to God. Let us get cleansing and purification by the Holy Spirit fire. Then we shall be bold again to preach His Gospel. True repentance is the beginning of a prophet's ministry. Confession of sin is where God's messengers are born. Peter confessed his sins to Christ, but that is when Christ called him to ministry:
Luke 5:8-10 (ESV)
But when Simon Peter saw it, he fell down at Jesus' knees, saying, "Depart from me, for I am a sinful man, O Lord." [9] For he and all who were with him were astonished at the catch of fish that they had taken, [10] and so also were James and John, sons of Zebedee, who were partners with Simon. And Jesus said to Simon, "Do not be afraid; from now on you will be catching men."
What sin can hinder us from God's calling and His Great Commission? Let us ask God to sanctify us with His truth, the Word. Let us be sprinkled with the blood of Christ, which cleanses us from evil consciences that we may serve the Lord. With God all things are possible. Even if we have fallen, God can restore us, that we may carry out His holy mission. Lord, cleanse us, send us, and speak through us, for Your glory. Amen.