TL:DR the authors of the bible got some details of the OT wrong, Jesus was made to quote Jewish thought that wasn't in the OT, and you could argue that since Paul invented so much it is basically a reboot.

Don't feel that way. An atheist shouldn't have to know this stuff, feel bad if you are a Christian. The answer is yes-and-no.

The authors of the NT didn't have the entire (for what we call now) OT, they had parts of it. There are about 17 (the exact number is debatable) writers of the 27 books of those only one could read Hebrew and probably had all of it. Why is this important? It is important because you see them, and Jesus, not aware of certain books and filling in gaps with what they wanted. Paul for example certainly acts like he didn't know the book of Micah. This is an example of retroconning by omission. Which isnt the worse I admit.

And we also have deliberate retrocons. Like the 1st Gospel of Matthew changing the genealogy to get the same ancestor distance between Moses and David and David to Jesus.

We also have plain mistakes. Matthew has Jesus get basic quotations from the Torah incorrect, Mark mixes up some historical details etc.

The big thing is that Paul was the one who threw out the Moses commandments. To him they no longer applied. He also invented ideas not really found in the OT explicitly stated. Original sin, the importance of baptism, the perfext sacrifice. So again a sorta reboot since the practice and ideas are now totally different.

Jesus in the Gospels incorporates ideas that were part of Jewish culture but weren't in the OT. You got to understand, the man most likely didn't exist, so the people talking about him could make him say what they wanted. The golden rule is not in the Bible but it is found in the writings of Hillel (rabbi who died half a century earlier) so they made Jesus say it. All those arguments he supposedly had with the Pharisees? Those were Pharisee debating positions of the time. In that sense I would say it is an add on.

Sorry a bit long. Did this all make sense? I prefer to think of it as a branch off of Judaism rather than a continuation. A branch off led by a con about a fake brother that got out of control.

Edit: oh shoot I forgot to add the most obvious one. The 4th Gospel, and people who love it, basically retroconned the Genesis story. The whole in the beginning there was the word and it was with God thing.