What should I say to my good brother who broke up with him?

The vulgar world is controlled by the evil devil, and the vulgar relationship between people in the vulgar world is a sin. To abandon it, according to the Bible, people must join the Christian church and become friends with noble Christians. Pursuing and doing God's will together is doing good. Please see:

the Bible

2 Corinthians 6: 14 You are incompatible with unbelievers, so don't be yoked together. What do justice and injustice have in common? What do light and darkness have in common?

What are the similarities between Christ and Belial? What is the relationship between belief and unbelief?

6: 16 What's the difference between a temple of God and an idol? Because we are the temple of the living God. As God once said,' I will live among them and walk among them. I will be their God and they will be my people. 』

6: 17 Jesus said to them, Come out from among them and be apart from them. Do not touch anything unclean, and I will receive you.

6: 18 I will be your father and you will be my children. This is what the Almighty said.