Greed

After getting pissed off at your local catholic church for not allowing you to do literally anything fun, you denounce your Christianity, slip into the church in the middle of the night, and decided to summon a demon. Though, honestly, you didn't even know what you were doing, what symbol you were painting, all that, so when you actually managed to summon not just any random demon but one of the literal Seven Deadly Sins, you and the one you summoned are confused