If a child, who is an adult, wants to live a homosexual life, does not want to listen to God's word, and does not claim to be a Christian, can a parent still talk to them? Can they visit their parents? Can they have a meal together?
The parents are members of the Lord's church and have made it clear they do not support the child and never will. They rarely see each other. They will talk on the phone. The child states the sin is like any other sin, like talking to a liar or a divorced adulterer who is not in Christ.
What to answer? What to do?
"I wrote you in my letter not to associate with immoral people; I did not at all mean with the immoral people of this world, or with the covetous and swindlers, or with idolaters, for then you would have to go out of the world. But actually, I wrote to you not to associate with any so-called brother if he is an immoral person, or covetous, or an idolater, or a reviler, or a drunkard, or a swindler--not even to eat with such a one" (I Corinthians 5:9-11).
The child is correct. His sin is no worse than other sins but it also is no better. He will not make it to heaven while remaining in sin and outside the Lord's Kingdom.
The rules about not dealing with sinners are limited to people who claim to be Christians while living an ungodly life. We have to deal with sinners in the world -- how else are we going to persuade them to be saved? However, this does not mean I need to support a sinner's lifestyle.
I suspect the parents have discussed their child's sin with him and they have reached an impasse. He isn't going to listen so he doesn't call often because he doesn't want to hear about his sins. The parents rarely call their child because they don't want to hear about his sins either. There really isn't much more that can be done until the child drops his pride and realizes that he needs God.