Religious Christians are like that, because they don't realise Jesus was the fullfilment of that law. Those laws existed, so the Savior of mankind could be born out of the Jewish bloodline.
So as far as laws goes; the old testament is indeed irrelevant. Jesus literally said he fulfilled the law.
I consider myself a Christian, but lots of Christians always forget or misinterprit "he without sin cast the first stone". Jesus literally means that every human is too flawed to accuse other people of being too flawed. Yet lots of Christians think they're without sin, simply because they accepted Jesus.
This is also the source of their homophobia, because they think they're sin-free like Jesus, and so these homophobic feelings "must come from God" they think. Which is a perfect excuse to blame/and hate gay people for the homophobia they feel.
Yet the whole point of having a relationship with Christ, is that you can tell him about things you struggle with. So if you experience homophobia, you just tell the Good Sheppard: "Yo my man, can you see this crap in my head? What's that all about?"
But some people, some christians, don't understand these things, so they don't talk to Jesus about it. It like when a christian is worried about money, they actually pray to God "please help me pay my bills", when instead they should be praying: "God, see how weak I am. Your word says to never worry, about anything, because you always provide everything I need to be happy. Yet here I am being a silly flawed human. Please give me some of your love instead. Amen".
Anyways. If you wanna understand Jesus better, you can watch movies such as Tron, the Matrix, or even better: The life of Brian. Also: God doesn't hate people. But he for sure doesn't like the fact that you hate yourself or hate others.