If I died and found out that some other Buddhism was true, then I'd thank whatever for the fact that I could try again, and perhaps get it right. I'd be glad, too, because I've always liked Buddhism.
If I died and found out Islam was true, then I would apologize to Allah, but say that I did the best I could while I was alive, and then it's off to hell with me...end of story. I guess that'd be the same thing with most other religions if they were the true ones.
If I died and found out there is nothing beyond earthly life, .... ...well actually I would never "find out" if this was true because I'd be dead. How...paradoxical.
If I died and it turned out that my beliefs were "correct", then...cool...I've got the rest of my afterlife to be thankful that I am able to be thankful because I've got the rest of my after life to be thankful....
Alright then