My moral conviction is that all honest, reasonable and decent people would like good to be rewarded and evil punished.

In order for all good to be rewarded and all evil punished, there needs to be created a category of existence called the afterlife because if we are confined only to this life, there does not appear to be an awful lot of good being rewarded or evil punished.

In order for it to be logical for us to believe that good will be rewarded and evil punished in this life and the next, God needs to exist to perform this function.

Therefore belief in God is both necessary and logical if we want good to be rewarded and evil punished.