Why would God base an entire eternal future on something as flimsy as a belief?

I partly agree with you. When I was younger I saw God like an imaginary friend I could talk to. As I got older it got harder to talk to him. Also I never agreed with the loving God that the church tried to sale you, I always saw him as more fierce. It's hard to explain, but that goes with the saying "those who believe, no prof is necessary, for those who don't no prof is possible".