When I studied puritan writing in my American lit class, it became clear early on that the fear of god was a tool used to keep order in a fledgling society. It's helpful, when you have an unstable system of law, to enlist the ultimate policeman/judge to do all the work for you; if you misbehave, you're going to hell. I think that's why atheism is so much more common in modern day society because we now have a complex law system in place that can be followed without the need for a god character. Belief still exists, however, because it provides an easy answer for an impossibly complex question (why are we here or how did we get here?). So, since we have a relatively stable law system, and we have scientific answers, the fear of god has largely become obsolete.