So, I'm interacting with a friend who's uses reason in every aspect of his life except his faith (aren't they the most disappointing?), and I've asked him how he dismisses all the horrible shit of the OT. I say that Jesus said laws are binding until all has come to pass. He claims Jesus' death was all coming to pass. He goes on to say that only those laws which are repeated in the NT carry over (eg homosexuality). So, two things: are all of the 10 commandments repeated in the NT? Because if not, he's got to dismiss them as well, right? Secondly, what's the verse Matt mentions in some random YouTube clip about god being unchanging and, therefore, all laws are in order for any and all times? It's the same clip he mentions the sermon on the mount, jot or tittle bit from Jesus. I think this would be much more irrefutable if it came from a specific verse. Any help would be much appreciated.

The quote you're looking for is Matthew 5:17-18:

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.

I tell you the truth, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished.

That's Jesus speaking, so there isn't much claim that Jesus somehow changed the old laws.

I don't think you will be able to win this argument. Religious beliefs appeal to passions and emotions, not to logic. Logical arguments wouldn't address the foundation of religious beliefs.

Sure, there are inconsistencies in the Bible. All creeds seem to find their way out of them. E.g., I can understand why Christians don't sacrifice animals - they claim that "Jesus paid it all". But why Jews don't do sacrifices? They claim, the law is a whole. One cannot break a part of the law, but remain "mostly good". No. You break one rule - you break it all. I've read in one book that Jews claim that the sacrifices must be done in the Temple at Jerusalem which was destroyed in 76 A.D. by Romans. Fine. But the Temple was built by Solomon, long after Moses. Isn't it just a lame excuse? Why not build a Tabernacle as Leviticus instructs? There are no instructions on how to build the Temple in Leviticus.

I can understand why Christians don't stone adulterers - "let he who is without sin cast the first stone", i.e. judge yourself before judging others. Or why Christians do not stone Sabbath breakers - "the sabbath was made for man, not man for sabbath." But why don't orthodox Jews stone adulterers and Sabbath breakers? Jesus is not an authority for Jews. It turns out that over the centuries, rabbis created layers upon layers of interpretations of the law. So, there is the written law - Torah (the 5 books of Moses), then there is the Talmud which is the rabbinic interpretation of these laws accumulated over centuries, then there is oral tradition passed in a form of allegorical stories (midrashim) which fill in the gaps and develop obscure concepts and characters.

Addressing religion with logic just doesn't work. Logical inconsistencies don't seem to matter to believers. You might try these questions as well. Why do Christians celebrate Christmas? There is no such commandment in the Bible. And why is it on December 25? There is no mention of the date in the Bible as well, and if there were, why is Easter observed by the lunar calendar while Christmas is observed by Gregorian calendar? Why are Catholic priests celibate? Apostle Peter had a wife. Doesn't creating images of Christ violate the second commandment (You shall not make for yourself a carved image, or any likeness of anything that is in heaven above, or that is in the earth beneath, or that is in the water under the earth.) What Santa Claus has to do with Christ? And why do many atheists celebrate Christmas? Etc., etc. As you try to answer these questions, you will realize that religious beliefs are based on deep cultural traditions and emotions, not on logic and facts.

The word of God doesn't change. Sure. But the interpretation does. In the west, we don't stone adulterers and Sabbath breakers, do not sell ourselves and others into slavery (literally speaking), etc. Even fundamentalists do not do that. It could be time to change the view on homosexuality now - we'll see.

I don't expect that you will change your friend's mind. This discussion would only be useful if you try to understand each other. I would like to know what your friend answers, though.

Faith seems unreasonable to those who claim to be reasonable, but those people will not find god through reason. This is what I have often heard from Christians and if true aces sense, considering we are not talking about natural phenomena that must be discerned through natural means. God apparently wants people to choose between this corrupt world or him. If God is the way and sin is rebellion, then if true would mean that it is the unbelievers who are unreasonable. I have often found it curious why Christians should not use the Bible to argue for their beliefs considering if it is true would hold up. Of course, it does require faith after all.