You have decided to say something to someone you love who does not share your faith. Maybe in a conversation, maybe in a letter. Either way, you are now looking at the blank space where the words are supposed to go, and nothing you try sounds right. Every version is either too much or not enough.
Deciding to speak and knowing what to say are two different problems. How to talk to your family about the rapture is about the first, the approach and the timing. This one is about the second: the actual words.
Begin with why you are saying anything at all
The opening words carry more weight than any others, because they decide whether the person keeps listening. Do not begin with doctrine, and do not begin with what happens after. Begin with them.
Something as plain as "I have been thinking about you, and there is something I have never said out loud" does more work than a paragraph of theology. So does "You do not have to agree with any of this. I just need you to hear it once." Both give the other person permission to listen without bracing for an argument, which is the only state in which anyone actually hears you.
Say the true thing, not the winning thing
The pull is to make the case: the reasons, the verses, the argument that will finally land. Set it down. It is not what they need from you, and it is almost never what changes anyone.
What to say is the honest, personal thing. What your faith has actually meant to you, in your own life, in plain words. Why it matters to you that they are in it. That your deepest hope is to be with them, in this life and beyond it. Keep it in the first person. "This belief carried me through the worst things that ever happened to me, and I wanted you to hear that from me" lands. "You need to understand that you are lost without this" does not — it only tells them what you think is wrong with them.
Be careful what you do not say
Some sentences close a door for years, and a few of them are the ones people reach for first. Avoid the deadline: nothing that sounds like a countdown or a threat. Avoid pronouncing the verdict on them, the "you will be left behind" line — fear rarely persuades and always wounds, and it is the surest way to become someone they quietly avoid. Avoid guilt, and avoid anything that makes your love sound conditional on their agreement.
A good test: read it back as though you were the frightened or grieving version of them, hearing it on a bad day. If any line would land as a threat or a reproach, cut it. What you want them to keep is the love — not the pressure.
When you cannot say it out loud
Some of this is impossible face to face. The relationship is too raw, the words dissolve the moment you open your mouth, or the right moment simply never comes. When that is true, write it instead. On paper you can take all the time you need, cut the lines that come out wrong, and let them read it without having to respond on the spot. Writing to someone who does not share your faith goes into how, and if the person is a child you have prayed over for years, praying for a child who is not saved sits with that particular ache.
Say the loving thing plainly, and if you cannot say it now, write it down so it is never lost. Write the letter and let it hold your words until they can be heard.