Anyone who takes a religious belief to the extreme and attempts to push their beliefs on others. The religion could be that of a strong atheist, or strong theist such as Christian but includes all deities. Both religions are beliefs. Atheism is considered probable by supporting evidence, but takes a leap of faith by considering it as fact. Theism is not supported by evidence, although a theist accepts all scientific evidence, but adds spiritual experience by taking a leap of faith that there is some sort of deity. Most people that don't push beliefs are agnostic, weak atheist, or weak theist.
You are just as much as a religious zealot as they are.