They Are Witness
“Verily, verily, I say unto thee, We speak that we do know, and testify that we have seen; and ye receive not our witness. If I have told you earthly things, and ye believe not, how shall ye believe, if I tell you of heavenly things? And no man hath ascended up to heaven, but He that came down from heaven, even the Son of man which is in heaven. And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up: that whosoever believeth in Him should not perish, but have eternal life.” John 3:11-15
Nicodemus sought out the Rabbi, Jesus, to inquire into Who He was. He knew that Jesus was from God, and that God was with Him, for the miracles that had already been performed. Jesus spoke to him about being born again, that is being born a second time, though this time in Spirit. Nicodemus didn’t quite understand, and Jesus replied with what you’ve read above.
What’s interesting is that Jesus says we and our. It is obvious that the we does not include Nicodemus, for Jesus is addressing him and He says “ye receive not our witness.” So, then is it He and the disciples that formed the we? Perhaps not. Jesus goes on to say that what He has spoken is of Heavenly things, and no man had ascended up into Heaven, except the Son of man, which is He, the Messiah. So, then if that be the case, then the only we which makes any sense is that of the Triune God, for they only had, at that time, seen Heaven, for Heaven was wherever They were, and it still is wherever They are. There is even other supporting scripture which shows that Jesus is part of the GodHead, when God is speaking to Himself in the garden of Eden.
“And the Lord God said, Behold, the man is become as one of Us, to know good and evil: and now, lest he put forth his hand, and take also of the tree of life, and eat, and live for ever: therefore the Lord God sent him forth from the garden of Eden, to till the ground from whence he was taken. So He drove out the man; and He placed at the east of the garden of Eden Cherubims, and a flaming sword which turned every way, to keep the way of the tree of life.” Genesis 3:22-24
So, knowing this is the perspective, which is from God’s point of view, we can see why He said what He said. He said that no man “hath ascended,” meaning it was already done, yet here He sat, in the flesh, yet to be crucified. He could say that only He had done it, having come down from Heaven, because from the perspective of an all knowing God, and being Three Persons as witness, outside of time and space, in all time, all of the time, He was already on the other side of that Cross in Spirit. This is why He also references what Moses had done. He was there, even in that very moment He spoke with Nicodemus, with Moses witnessing the event take place. That very event which was a foreshadowing of what He was about to do in the physical. All of this was connected in Him, and manifested in Him, and witnessed by all Three Persons of the GodHead.
Jesus said one other thing which should not go unnoticed. He said, “no man hath ascended up to Heaven, but He that came down from Heaven, even the Son of man which is in Heaven.” How else could He say this very thing and still be speaking the truth? Notice that He refers to Himself as saying He came down from Heaven, and was, yet, right there with Nicodemus, and was still in Heaven. How could this be? It is so, because Jesus is God, outside of time as we understand it, in every moment simultaneously. He is a part of the Triune GodHead, and they are witness to all things in Heaven and on Earth. The Word of God is Their testimony.