Humans create religions in an attempt to make sense of the world and encourage social stability. They base their ideas on current scientific/intellectual and moral standards, combining current ideas about the world with what they consider plausible speculation about the unknown (and it is precisely 'the unknown' that they desire to explain or have explained).
In the case of constructing an explanation for the origin of the universe and human life, and what happens after death, in the absence of relevant evidence, widespread ideas about deities and the afterlife were available as models - all major religions have basically similar explanations of how the world was created and the afterlife, only the details are different. (Deity creates heaven and earth, creates man in his image, establishes cloud or feasting hall with carousing, virgins or harps where pious men can spend eternity after death.)
Adlerian psychology describes ‘guiding principles’, constructs that people create to help them make sense of the world and then assume to be true (and act accordingly, etc.). People establish these guiding principles in response to psychological and intellectual impulses and in accordance with their existing understanding of the world. Most of the guiding principles we use in everyday life tend to be fairly reasonable, being based on evidence and rational thought. In the case of Creation and the afterlife, however, these factors are necessarily absent (obviously - they don't exist).
Normally, guiding principles are adapted and discarded in light of new evidence or more advanced understanding, but this is not possible in dogmatic belief systems. The fundamental flaw of major religions has not, therefore, been their failure to provide accurate explanations, but their inflexibility: 'this is the true God, you must worship him!' In a manner similar to the friction that develops between religious (dogmatic) morality [see my discussion at http://atheistprinciples.tripod.com/discussions.htm
] and social reality, the explanations provided by religion become increasingly at odds with scientific/intellectual standards, resulting in a decidedly negative influence on the intellectual development of both individuals and society in general. This is why religious superstition should be actively opposed - its potentially damaging effect on clear thought is a real and significant social and psychological problem.