How should Christian parents respond if one of their children comes out as gay?

If a child reveals his or her homosexuality, the first thing for
Christian parents to do is let their child know that, no matter what,
love and grace will win the day. Mom and dad's love will continue,
regardless. First John 4:8 says, "The one who does not love does not
know God, for God is love." "God's kindness is intended to lead you to
repentance" (Romans 2:4).

All parents need to remember that our children (like ourselves) have
heart issues. We're not trying to put good fruit on bad trees; we are
passionately praying for our wayward children that God would change
the roots of the tree—that He might remove their heart of stone and
replace it with a heart of flesh (see Ezekiel 36:26).

Parents should also encourage a child who has "come out" not to define
himself as a "homosexual." It's important to ask questions: Are you in
a relationship? Is the relationship sexual or platonic? Have you acted
out your feelings of same-sex attraction, or are they just thoughts
you have? Parents can come alongside a struggling child and help him
see that he is not "gay" simply because he has homosexual thoughts.
Rather, he is struggling with homosexual desires or same-sex
attraction.

The difference between struggling with homosexuality and identifying
oneself as gay may seem subtle, but it is a huge distinction, and
here's why. God never created us to be homosexual. In Christ that is
not who we are. In Christ we are a new creation. Christians may
struggle with impatience, idolatry, lust, or pride. Christians may
struggle with same-sex attraction, but that does not make them
homosexuals. We are new creations in Christ.

So, Christian parents can approach their child as broken people and
offer to struggle together through their imperfections. It is
important that we never communicate to those who have same-sex
tendencies that their sin is the worst of all sins. Yes, homosexuality
is sinful, but not to a level above that of heterosexual lust or lying
or pride. The truth is we are all broken, and we all need help to
remain pure.

Also, Christian parents should make clear their biblical convictions,
but only after they have established a basis of love and grace and
empathy and compassion. Your children need to know that the Bible is
the supreme authority on all matters of faith and conduct. Not mom,
not dad, not peers, not the church. And the Bible says that
homosexuality is counter to God's intended purpose for human beings.
Sexuality must be heterosexual in nature and within the boundary of
marriage.

If a child says, "I am homosexual. That's the way it is, and I don't
care what God thinks," then clearly the parents are back at step one.
This child needs a serious heart change, and only God can change the
heart. Sin is a heart problem, and until God changes the heart and the
child is gripped by the grace of God, nothing will matter. A parent's
convictions will not matter. The letter of the law will not matter.
Love is key. It is what drove the prodigal son back to the arms of his
father (Luke 15:11–32), and it is, according to the apostle Paul, the
greatest of gifts (1 Corinthians 13:13).