The gay and lesbian communities are very familiar with the Christian, Biblical position on homosexual relationships. Your son doubtless knows you cannot condone homosexual practices. What should a parent say to his gay child?
Whether a sin seems large, like murder, or a sin seems small, like a white lie, the wages of any sin is death (Romans 6:23). Do my family members choose to confront most or some of my sins? Not usually. If they did, a great percentage of our communications would be about my sins and their sins. No, they know I am aware of my faults. They also know God is working in me to help me. (Phil. 2:13) God is the one who softens our hearts to see, to repent, and to work on our sinful tendencies.
When would Jesus confront a sinner with his sins? Would He require repentance before He healed him? John 5 records the story of the crippled man waiting by the pool of Bethesda. Jesus healed him and the man immediately began walking. A short time later, “Jesus found him in the Temple and told him, ‘Now you are well; so stop sinning, or something even worse may happen to you.’” It was after the man was healed that Jesus cautioned him.
When a person is open to hearing a reproof, that is the time to offer wise words. Otherwise, unsolicited counsel offered to a closed heart/mind tends to generate anger. “Reprove not a scorner, lest he hate thee: reprove a wise man, and he will love thee.” (Proverbs 9:8) Timing is critical to any conversation. Jesus said, “I have yet many things to say unto you, but ye cannot bear them now.” (John 16:12)
So, how might a parent relate to his son practicing homosexuality? I would try to follow Jesus’ example in the way He related to sinners. First, Jesus maintained His own sinless life and was a shining example of righteousness. Additionally, His love would draw sinners to Him. They knew His compassion, forgiveness, and grace. If it is possible, I would maintain a grace-based relationship, but within your home, not permit behavioral immorality. Furthermore, I would avoid engaging in activities with your son which support homosexuality. Where you draw the lines depends on you. It is a very personal decision. However, it is critically important for you to maintain a clear conscience with God and man.
Finally, ask God for wisdom, patience, and strength. The Christian grace of long-suffering is only developed by experiencing long-suffering. This sounds like it may become a very painful and long-lasting trial. But Jesus has promised, “I will never leave thee, nor forsake thee. So that we may boldly say, The Lord is my helper…” Hebrews 13:5, 6.