I don't recall saying anything about Christianity being unique? It's only uniqueness is the foothold and community in Western countries, usually providing familiarity even in a strange town. My wife used to have a little state of Mary in our very rural front yard, and we once had a young lady that knocked on our door whose car had broken down and she took it as a sign of welcome and willingness to help strangers.
Yeah, that's in the Old Testament, but I'm not recalling Jesus' Sermon on thd Mount saying "yea verily shalt thou bone a bitch proper if her husband disses thee". Salad bar and all that.
This gets argued a lot, and Jesus also said that he brings the New Covenant, that supercedes the Old. The Old was fulfilled, and hence continued its morphing, as the Law allowed.
Jesus didn't change a word, but his existence brought the changes on, in accordance with the old laws, which allowed for the messiah to change the game. Nothing changed in the law, because the law always allowed for this to happen