The Blasphemer God was once a mortal man. A devoutly atheist man; he was also a mage of some caliber. He dedicated his life to proving that the Gods were nothing more than powerful celestials and demons, creatures not fitting for worship. His increasingly convincing proselytizing skills gathered him a large following, numbering in the tens of thousands. He called the entire congregation together, and showed them a miracle. He said that he too could create Heaven, and he was just a mortal man. He created a demiplane before their very eyes, and their adoration washed over him, causing him to transform. He awoke some time later a changed man. Not a man…a God.
It was only then that he realized the error of his ways. Initially he felt angry that the Gods didn’t come down and show him proof of their existence. Surely he had committed serious blasphemy? He went to a Greater Power, and begged an audience. This particular God is lost to history, some say it was Asmodeous, some say it was Rasitlin, some say Zagyg. They can all agree on one thing. The God said unto his new fellow Deity,“And who are you, that we The Divine, Creators of Existence should deign to appear to you?” Humbled by this, the Blasphemer resolved to permanently give up his mortal name, and become patron of the misguided.