Atheism isn't a religion, true, but human beings are innately 'religious'. Anyone can be a zealot about anything, including godlessness. Marxism, and all it's quasi-denominations, have killed the most people in all of human history, and it is a philosophy that is vehemently anti-theist, anti-deist and anti-Christian.

As for this asshole with the gay devil shoes, yes it is on the surface meant ot be a middle finger and a troll. But you must also understand that only mockery of Christians and Christianity is permitted and encouraged in our culture. Criticism of other ideologies/religions is considered bigotry, racist, xenophobic, etc., etc. So, why is that always the case? It may be because evil is where their allegiance is; rebellion against all that is Godly. This isn't anything like the Ozzy Osbourne theatrical aesthetic, they are smearing shit in our face because they are wreaking havoc on the culture and loving that they can corrupt all who are drawn into it.