There is a particular kind of prayer that a parent prays alone, usually at night, and often for years. It is the prayer for a grown child who does not believe. You have prayed it so many times that the words have worn smooth. Some nights you are not sure you are praying at all anymore, so much as aching in God's direction.
If that is you, this is written for you. Not to tell you what you are doing wrong, because you are almost certainly not doing anything wrong. Only to sit with you in it for a few minutes, and to say some things that are true.
You cannot save them, and you were never asked to
The heaviest part of this is the quiet sense that it is your job to fix. That if you had said the right thing, or raised them differently, or prayed harder, your son or daughter would believe by now. So every day they do not is a day you failed.
That burden is not yours, and it was never handed to you. No parent has ever saved a child. You cannot argue anyone into faith, and you cannot love them into it either — though love is far closer to the point. Salvation is God's work, from start to finish. Your part was to love them and to tell them the truth, and if you have done that, you have done your part.
It helps to remember who is actually waiting for them. "The Lord is not slow in keeping his promise, as some understand slowness. Instead he is patient with you, not wanting anyone to perish, but everyone to come to repentance" (2 Peter 3:9). Your longing for your child is real, but it is a small thing beside God's. He is not tapping his foot at their unbelief. He is patient in a way you cannot be — and he has more time than you do.
Pray for the person, not only the outcome
It is natural for this prayer to shrink down to a single request repeated over and over: save them, save them, save them. That is a good prayer, and you should keep praying it. But a child who does not believe is still a whole person with a whole life, and they can be prayed for as one.
Pray for their loneliness. Pray for the friend or the stranger who might one day say a true thing you are not in a position to say. Pray for the moment, perhaps years from now, when something breaks open and they are finally ready to hear what they cannot hear today. Pray that you will still be close enough, and still gentle enough, that they will come to you when it does.
Keep praying even when nothing seems to change, because you are almost never praying on the timeline you can see. Augustine's mother, Monica, prayed for her son for years while he wanted nothing to do with her faith and a great deal to do with everything she feared for him. She did not get to schedule his change of heart. She only got to keep praying until it came. In the story Jesus told, the father sees the younger son "while he was still a long way off" (Luke 15:20), which means he had been watching the road the whole time. That is most of what this prayer is — watching the road.
Keep the relationship open
The danger, when you care about something this much, is that the disagreement slowly becomes the whole relationship. Every visit starts to carry the weight of the thing unsaid, or the thing said too many times. Your child begins to brace when your name comes up.
Do not let it get there if you can help it. The relationship is the one thing you can actually tend, and it is also the thing most likely to matter later. A person who feels judged closes the door. A person who feels loved leaves it open, and an open door is where the real conversation eventually happens, if it happens at all. If you do want to talk about it directly, how to talk to your family about the rapture is worth reading first, because the approach matters far more than the argument. It also helps to know the difference between readiness and anxiety, so that what your child hears from you comes across as love rather than fear.
Say the thing while you can
Underneath all of it, there is something you want your child to know. That they are loved. That your faith was never really about being right, but about wanting them with you, always, including in whatever comes after this life. Most parents assume there will be time to say it plainly. Often there is not, or the moment never arrives, or the words come out as pressure when you meant them as love.
You can say it now, out loud, imperfectly. What your children need to hear from you is usually simpler and less doctrinal than you expect. And when the conversation is genuinely not possible, when the estrangement runs too deep or the subject is too raw to raise, you can still write it down. Writing to someone who does not share your faith is often easier on paper, where you can take your time and they can read it without having to answer on the spot. If you do sit down to write it, how to write a rapture letter to your family walks through what to put in one.
A letter waits without pressure, and it can hold the thing you were most afraid you would never get to say. Write the letter to your child, and let it keep your words safe until the day they need them.