That's only an issue if they are wrong about "the next life".
Not to mention, you're mixing *vastly* different belief systems, here. Modern Christian fundamentalists, especially those in America, believe the opposite: that God wants them to be just as happy and prosperous in this life as in the next. It's only poor liberal saps like me who think suffering is a blessing*.
FuMan
* and by "blessing", I mean that in the technical sense of "something you get when you keep the terms of the covenant". Note also that that's only the new covenant under JC; Judaism is blissfully free of elevating suffering to Godlike status.