Why can’t we agree to disagree?

I’m marrying into a very VERY religious family. (Think like the Duggars type, no shade) My beliefs are overall more spiritual but I also think many things can be true at the same time. I find it very beautiful that a lot of religions overlap. I guess I just overall believe in being a good person and being kind to others. I do believe in God and Jesus and would’ve considered myself a Christian until meeting these people. My future husband’s family has been the most difficult and hateful people I’ve ever dealt with. They have problems with everything, from us living together (and having pre marital sex) to the fact we aren’t having a pastor officiate our wedding (my dad is the officiant.) they really hated that we aren’t getting married in a church. His sister and her husband have even said we are a dangerous role model for their children and won’t let us see/speak to them anymore until after we are married. (Their kids were supposed to be in the wedding and they’ve changed their minds now 3 months before hand) There is so much more but these are just examples of the stuff I deal with on a daily basis. I’ve asked why we can’t just agree to disagree? I’m very respectful towards them and the way they chose to live their lives, but they refuse to be respectful towards us. They say it’s out of “love” that they tell us how sinful we are being. They say if we weren’t believers it wouldn’t matter, but because we both claim to believe in God that we should be ashamed in the way we are starting our marriage out. Am I missing something here? I’m not gonna pretend I’ve read the Bible but I know the basics, and it doesn’t seem very “love thy neighbor” of them. Also, if it’s my sin, isn’t it my judgement? It’s people like this that make me want to give up completely on the entire religion.