I do not believe in God and have not for as long as I can remember.
Despite going to religious schools, which involved prayers every morning, hymns multiple times per week, I never truly believed.
When I was in my teens I was convinced (as are many fedora-tipping redditors) that religion was the main source of conflict in the world and if we can only spread atheism the world would be a better place.
As such I routinely attacked Christianity. But I also was not afraid to attack Islam and Judaism, as many self-identified atheists are today.