Would you still serve God if there was no hell in which to be punished for your evil? Would you still serve God if there was no heaven in which to be rewarded for your good? Would your behavior change at all?
I would venture to say that most church-going Christians serve God, not out of a desire to be in relationship with God, but out of a desire to avoid hell. If there was no hell, they would not serve God, or at least would not continue to live the way they do morally speaking. While desiring to avoid hell is natural and a good motivator for initially deciding to serve God, it is a very poor motivator for continuing to serve God.
I don’t necessarily want you to respond in the comments section with your answers, but I do think this is something worth thinking about in the way of self-evaluation.
Update on 6/21: A new study appearing in the Public Library of Science journal, PLoS ONE, has evaluated crime rates involving 143,197 people in 67 countries over a span of 26 years and found that crime rates are lower in nations that believe in the possibility of some sort of divine punishment after death, and higher in nations that do not (or that only believe in divine rewards after death).