Good points. I tend to agree with most made, I don’t agree though that “believers” must be “Christians.” Plenty of religious and even non religious believe in an afterlife. I always believed in one and even a before life too, which no one much speaks to.
Anyway Hinduism, for example, speaks to many lives being lived before a blissful state of nirvana is reached in a lasting afterlife. And the Tibetans die and come back and speak of their journeys to the afterlife. They believe one can go back and forth, and so they do.