People, your child included, rarely come to true faith, become assimilated into Christ's story, due to intellectual discussion or convincing argument. Most people come to Christ through a profound, ongoing relationship with a authentic Christian. This is why it is so important that you as a parent have an active faith and demonstrate to your child that you really do love them and you love, not the philosophy of but the person, Jesus Christ. Clarity in these two relationships overcomes almost all obstacles and shifts people to a position where they can accept that this God-story is true. "This is how they will know that you are my disciples, if you have love for one another." John 13:35. Grow yourself transparently towards God and towards them.
The last step in bringing your child to faith is helping them find their place in the story. Now Hear This....this does not mean telling them what they should be doing in the church or on Sunday. Helping them find their place means celebrating any activity that they do and orienting it to Christ. Instead of taking them with you as a part of your story like in section "B", now it is time to let them know that you think they are great and have wonderful things to offer in Christ's story. "You really are a good artist. That work would look great in the Parish Hall." "This is a great omelet! The Men's Hike guys would love this." Planting seeds. It will help your mission to talk to ministry leaders, explain your child's talents and ask them to ask your child for help.
A final word: you are long past telling them they need to change. Hasn't worked so far and won't work now. You are now adult acquaintances (not even friends yet) so treat them that way. You wouldn't tell an acquaintance to get their act together. You would ask, "How are things going? You look kind of down." And then you would simply listen. And pray.