The Jews answered him, “Are we not right in saying that you are a Samaritan and have a demon?” Jesus answered, “I do not have a demon, but I honor my Father, and you dishonor me. Yet I do not seek my own glory; there is One who seeks it, and he is the judge. Truly, truly, I say to you, if anyone keeps my word, he will never see death.” The Jews said to him, “Now we know that you have a demon! Abraham died, as did the prophets, yet you say, ‘If anyone keeps my word, he will never taste death.’ Are you greater than our father Abraham, who died? And the prophets died! Who do you make yourself out to be?” Jesus answered, “If I glorify myself, my glory is nothing. It is my Father who glorifies me, of whom you say, ‘He is our God.’ But you have not known him. I know him. If I were to say that I do not know him, I would be a liar like you, but I do know him and I keep his word. Your father Abraham rejoiced that he would see my day. He saw it and was glad.” So the Jews said to him, “You are not yet fifty years old, and have you seen Abraham?” Jesus said to them, “Truly, truly, I say to you, before Abraham was, I am.” So they picked up stones to throw at him, but Jesus hid himself and went out of the temple. John 8:48-59.
Jesus does not want to come right out and say, “I am the physical manifestation of your God, Jehovah.” To do so will bring things to a head too quickly. So He gives them clues when they keep asking who he is. When He finally says, “Truly, truly, I say to you, before Abraham was, I am,” He has said enough to provoke an execution by stoning, and He has to get out of there. Identifying Himself with “I Am” places Him not only with Abraham, but with Moses at the burning Bush.
In the beginning of the Gospel of John, we are quite explicitly told that in the beginning was the Word, and that the Word was WITH God and WAS God. And we are told that the Word was made flesh. This is Jesus. This is our God. As the Word, He had been communicating with His people for generations. But to fulfill His mission to redeem mankind, He had to become a man. He had to have a body, so Mary was chosen to birth Him into the world. And for God to be the Father, He would have to come to inhabit her supernaturally. And her lineage helped Him fulfill His role as God’s high priest. Mary was a descendant of the priestly family of Levi.
Jesus’s Preexisting condition as the great I Am qualifies Him as worthy to take away the sin of the entire world. We never have to wonder if His sacrifice was sufficient. Nor do we speculate about there being other ways besides Jesus. There is no substitute for God Himself taking your punishment so you can reign with Him in Heaven.