Question: Did Martin Luther believe in Satan?, Answer:Yes, Description of Martin Luther: Saxon priest, monk and theologian, seminal figure in Protestant Reformation, Fact1: Martin Luther was a Protestant., Fact2: Satan is also known as the devil., Fact3: Protestants traditionally have believed in the devil as a being. 
Step1: What religion was Martin Luther?, Step2: Do #1's believe in the existence of a non-human evil being (Satan, Beelzebub, the devil, etc)?, Wikipedia page for step 1: Martin Luther, Wikipedia page for step 2: Protestant (beliefs), not_definitive_answer: False, incorrect_answer: False