Ben Thomas, from Florida-based Spike's Tactical, said the gun "would never be able to be used by Muslim terrorists to kill innocent people or advance their radical agenda."
Speaking to Orlando Sentinel he said the weapon had been inscribed with Psalm 144:1.
It reads: "Blessed be the Lord my Rock, who trains my hands for war, my fingers for battle".
The gun's safety lever features the words 'Pax Pacis' 'Bellum' and 'Deus Vult' which mean peace, war, God wills it.
"Off the cuff I said I'd like to have a gun that if a Muslim terrorist picked it up a bolt of lightning would hit and knock him dead," Thomas said.
The gun's been criticised by Muslim campaigners who say it promotes racism.