Jesus taught the Old Testament as the authoritative word of G-d, but he also attempted to fulfill it and sometimes challenged the rigid interpretations imposed by religious leaders of his time, which could make it appear as though he was defying certain aspects.
This isn't a simple either/or; his approach was to affirm the Scriptures' divine origin while revealing their deeper intent and bringing them to completion through his life, death, and resurrection.
A key statement from Jesus himself clarifies his stance: "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them". He was teaching the Torah, after all, he didnt write the New Testament obviously, so what other book would be the authority?
Therefore, at the end of the day, the greatest difference in terms of beliefs, (not rituals), is whether you believe Jesus was the Mashiach or not. If you believe he was, you are a member of Christianity, what is in effect a sect of Judaism.
Jesus didn't 'attempt' to fulfil, all of the Old Testament, He did and still will fulfill it. Jesus did oppose the religious leaders of his day. Not just in 'appearance'.
(Mark 11:15-18) "And they come to Jerusalem: and Jesus went into the temple, and began to cast out them that sold and bought in the temple, and overthrew the tables of the moneychangers, and the seats of them that sold doves; And would not suffer that any man should carry any vessel through the temple.
"And he taught saying unto them, Is it not written, My house shall be called of all nations the house of prayer? But ye have made it a den of thieves.
"And the scribes and chief priests heard it, and sought how thy might destroy him: for they feared him, because all the people was astonished at his doctrine."
Many often overlook the seriousness of this event. What priests and Pharisees and religious leaders were there did nothing to stop Jesus. He acted in this manner with all authority from Heaven. And note what he said in (15:17), 'My house'. And in (John 2:16) we are told He said, 'my Father's house'. Perfect equality with the Father. And in (John 2:15) we are told He made a whip and drove them out.
I say to anyone, much less a Christian, go to Jerusalem today and walk in a synagogue and start destroying it and running the people out of it, and see the reaction. That would have been the same reaction in Jesus day had it not been Jesus that was doing it. Jesus was opposed to Judaism. Not the Old Testament Scriptures. Which He also fulfilled in this act. (John 2:17) "And the disciples remembered that it was written, The zeal of thine house hath eaten me up." See (Ps. 69:9)
Jesus was teaching more than the Torah. He said, (Matt. 5:17) "Think not that I am come to destroy the law, or the prophets..." He wasn't just talking about the Torah. He was talking about the whole Old Testament Scripture. 'The Prophets'.
Christianity is not a sect of Judaism. Jesus was opposed to Judaism and Judaism was and is opposed to Him. Judaism is the false sect of God's true faith as revealed in the Bible. Just as Judaism opposed Jesus, so it opposes Christianity.
Jesus said, (John 5:46) "For had ye believed Moses, ye would have believed me: for he wrote of me." Judaism rejects the Person of Jesus Christ. They reject Moses also. They are the false sect, not Christianity.
Quantrill