That’s a tough one… but I was raised in church ⛪️ I haven’t been for years but I would say to him in the book 📕 of Mark 13:32 “But of that day and that hour, no, not the angels which are in heaven, neither the Son, but the Father. Take ye heed, watch and pray”
He actually referenced that passage, but then proceeded to explain why he's convinced he's right due to numerous other reasons. The conversation went on for about two hours and was largely one-sided. I just wanted him not to do anything that would be irreversible if he were wrong.
I am not a Bible expert by any means I would just say “if the angels in heaven don’t know why would you?” Many people have tried to guess for years. I remember 50 years ago in church the minister said he’s coming soon, and here we are.