Let's take the natural explanation first. Of what we think happens after we die right now, you will not even be in a state to comprehend whether you're alive or dead, let alone whether there is a god and if any of the religious texts are true. When you die, you cannot get a glimpse of the darkness before saying to yourself "oh fuck, there is no god", and then die for good. Considering that, you only have this one life to see, hear, feel, touch, admire, appreciate and comprehend everything, it's best that you do all of this while you can rather than do it in an afterlife that you'll possibly never experience.
Also, what guarantee do you have that this god is gonna reward your faith or your belief in him? What if this god, who has an identity, is not satisfied with people(like you) believing in an abstract definition/concept of a god? What if those people are going to hell because they did not worship a particular identity of god as described in some religious text you never studied?
Even if you do believe in the concept of a god, there are just too many unknowns which make it impossible to do so just in the hope that there is an afterlife.