We learn from the Bible that we are ALL made in G-d's image..
..believing a man to be G-d, is very important to Orthodox Christianity..
It all revolves on a man "dying for our sins", and rejecting Jewish law.
..if Jesus is not G-d, it all comes tumbling down .. oh well.
If Jesus is not sinless then it comes tumbling down yes. In that case Jesus would not be able to die for the sins of anyone because His death would have been deserved and be the wages for His own sins.
Jesus did not come to do away with the Law, He came to fulfill the law, or so He said.
The law and the Covenant of Moses was a type of the New Covenant.
Jesus fulfilled the sacrificial law by being the spotless lamb sacrificed for sin (except with Jesus it only needed to happen once to cover all sin)
Jesus fulfilled the moral law by being sinless, not breaking the law.
Jesus replaced the law of Moses with the law of love and with the Holy Spirit to guide us in that. The Law of Moses was not rejected, it was replaced and upgraded in both the moral law and the sacrificial law, and the laws of feasts also relate to Jesus and what He would do.
Adam and Eve were made in the image of God and I suppose each new born is also made in the image of God, but we all sin and fall short of that image.
Jesus was the only one who did not fall short and that is because He is good and is God. He was tempted as a man but did not sin.
So Jesus being sinless is important for Christianity and that means that Jesus is YHWH, because only God is good.
The thing is that it did not all come tumbling down unless you deny what the Bible and Jesus tell us and believe what someone else might say about Jesus and the gospel story and the OT prophecies concerning the Messiah. Someone who may be anti the Messiah.