We all come to Christ with different backgrounds, cultures and understandings of God. That means some people come with a strong background of who Christ is, and how he expects us to act. They may have been living in a godly home, with parents who raised them to understand the love of God, and how Christ expects us to treat one another. They can be shining examples probably from the beginning of how to be God's hands and feet in this world.
Others may come from abusive homes. They may have learned to defend themselves with nastiness and even physical strength. God has a big job changing these people, and it is probably going to come gradually, with much repentance, weeping and help from the Christian community.
Others barracade themselves behind being cruel or nasty, so they do not get hurt. Their hearts are hard, despite their relationship with God. God has a lot of work to do to move these people to a place of putting others before themselves.
But he will do it! He does change hearts and lives - one piece, one person, one step at a time. Sometimes it takes a long time to see that fruit. It may seem like the person is not changing.
But if they are truly saved, God is transforming them by the power of his Holy Spirit. I know there were times in my Christian walk that I looked like I was doing well. But it was me acting! Then there came a period where I was a nagging, angry shew. I was hurting, had unresolved conflict from my youth, my marriage, and work was also adding to my stress. My husband told me many times I wasn't a Christian. I was, but I needed God to really change me! I went from being an hypocritical actress to showing the real hurting me, and it wasn't pretty. It was part of the breaking process to remold me back into the treasure God had created.
Then God really let me fall, and used it for his glory. He gathered me back and the Holy Spirit began an incredible work! God showed me how hurting I was, and that I was not the only one! He reconciled me to my birth family. He taught me to be the one who reached out in love.
I marvel each day at how far God has brought me. And how he changed my husband, and has given us both his peace.
You need to look at these nasty people and ask "How can I help them?" "How can I be a friend?" If they resist you, there is a point you do need to move on. But instead of making their behaviours about you, or even about God, why not be someone God can use to be a friend to those who are hurting?