This is tough. There’s nothing more heartbreaking than watching your adult kids fail spiritually. I know first-hand. You feel like a failure, even though you KNOW it’s not your fault. Many of us believe our kids are saved, but just have fallen away. Perhaps, though, we should start treating them and praying for them as we do non-Christians. As we witness to our unsaved friends, we’re not constantly pointing out the sin in their lives. The best way we can lead them to the Savior is to love them. That doesn’t mean condone their behavior—but love them unconditionally. That kind of love is irresistible. If it doesn’t lead your kids back right away, maybe God will deliver your grandkids.