Is it a sin if you are having intercourse with your ex-husband? The reason for divorce is adultery. He has a girlfriend but denies it. He is a born again Christian. I still love him but he never speaks about making up, we only have intercourse. Is this biblically wrong?
"Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4)
But you're having sex with a man to whom you are not married. Thus it is adultery. In addition, you are being played the fool. You divorced the man because he broken the marriage covenant. You know he is having sex with another woman, but you still want him in your bed. Why should he straighten out his life? He's getting sex from at least two different women without any commitment from either one.
"Whoever divorces his wife and marries another commits adultery; and whoever marries her who is divorced from her husband commits adultery" (Luke 16:18).
His claim to be a Christian doesn't change the truth. He is a man living is sin and heading to hell unless he turns from his sins. "Not everyone who says to Me, 'Lord, Lord,' shall enter the kingdom of heaven, but he who does the will of My Father in heaven" (Matthew 7:21). Since he is not doing the will of God, he cannot enter the kingdom in his present state.
What I hope you see is that you don't want to follow him. Please repent of your sins. Throw the bum out and only accept him back when he is willing to leave his life of sin and has married you again.