If you undergo a Salvation experience but then become an atheist, the experience does not trump the fact that you are an atheist at time of death. Claiming the experience wasn’t real because the person later became an atheist is a self-fulfilling prophesy and therefore irrelevant as an argument. Baptist love to tell people they are going to Heaven.
There are way too many people going to Hell because someone declared them to be Saved based on a prayer and a bunch of water. There is too much hallelujah and not enough fear and trembling.
A lot of old testament prophets fell away and displeased God after they had fulfilled their roles.
Only the Holy Spirit can tell someone that they are saved.
I knew a girl in college. She was a Baptist, active in all the youth groups. The she became a Jehovah’s Witness. In less than a year she switched to Mormonism. Astounding really because the JWs really hate Mormonism.
Then she switched to some Far East Sect, Hari Krisna maybe. The point is, she never believed in any of those.
I long ago lost track of her. But when I think of her I make a prayer that she finds her way to Christ. You would do me a favor if you said a prayer for her too.