Many of our wayward children are miserable no matter what facade they present to their friends or to us. Those Prodigals are slopping with the pigs in spite of how happy and boisterous they appear.
What do we do when our children who professed Christ at one point in their lives are living like the world? How do we reach them when they have heard it all before, and can parrot the gospel back to us even though it seems to mean nothing to them? What do we say to a daughter or son who posts Bible verses on their MySpace or Facebook and lives an immoral and godless lifestyle otherwise?
The sad truth is that their hearts may not have been affected by the truth. It is one thing to know the truth and another to believe the truth. With this in mind, challenge the child with what Paul said in 2 Cor 13:5, test yourselves to see if you are in the faith, examine yourselves!
Remind them that their salvation is not evaluated by something they have done in the past (pray a prayer, walk an aisle), it is evaluated by the present. In the examination process, there must be evidence of a new life, there must be something to convict them of being a Christian beyond their words.
No judge in the world would take only the word of a person who confessed to a crime if there was no evidence to back it up. Plenty of unbalanced people have claimed to be famous killers but were released from police custody when there was no proof to connect them to the crimes no matter how much they proclaimed they were guilty. Similarly, a person who claims to be a Christian but has no proof of their claim cannot be believed either.
A person who is a Believer will have evidence in their lives of their claim. There will be an ongoing desire for holiness and an increasing hatred of their sin (Rom 7:15-25). It is not as though they are sinless, but progress in holiness is evident. If their life is characterized by sin and disobedience it is possible they are living as disobedient Christians, but it is far more likely they are not saved at all. They (and you) have to face the fact that they are not truly a Christian.
This is the hardest for us as parents because we hope beyond hope that we are wrong and they really are saved. The feelings of grief and sorrow go so deep when we realize our beloved son or daughter is lost and in eternal danger. It breaks the hearts of parents who have poured their lives into their children and raised them according to biblical principles to see their kids reject Christ.
All we can do is to continue to pray for our children and point them back to the cross over and over. We must continually challenge their thinking and lifestyle- not with our own preferences, but by the standard of the Word of God.
Let them know you love them over and over, despite how they behave. It is most difficult to love someone who is "unlovable" but God will enable you to do so.