For me (and I realize it may only be for me), that completely obliterates the meaning of "true". You've expanded the meaning to include "those things you want to be real". It's not that I think "true" is restricted to boolean options of true/false, but in between are the unknowns, the things we think might be true, etc. Lots of things live between true and false, but to stomp your foot and say something is true because it would be better for you if it was, is actually closer to the sort of "truthiness" that Colbert talked about a few years ago.
So if you want to call life after death an example of truthiness, that makes sense, because that's what it is - you feel it is true, so the truthiness of it speaks to you. To me, it's make believe bulls**t of the sort that religion trades on to expand its appeal, and I won't be manipulated by what appears to be an ancient con game, and for which there is no evidence whatsoever. I can not even be forced to believe it with a gun to my own head. I could lie, I suppose, but I couldn't actually believe it. For whatever reason, I can not bring myself to believe those things for which there is no evidence in favour, and plenty of reason for someone to lie.