This paper aims to illuminate the influence of trauma on the life of Joe Christmas, the main protagonist of William Faulkner’s Light in August. The childhood trauma of Christmas is presented as flashbacks, and the writer tries to represent Christmas as a trauma victim who is in a continuous search for identity. His early traumatic event occurs in the orphanage when he accidentally witnesses the dietitian’s intimate relationship, and she calls him “nigger bastard” in a rage. These words leads Christmas, who looks white, to experience an identity crisis. He tries to be white or black, but he fails to belong to either side. In the end, he repudiates the harsh dichotomy of Southern society and leads an alienated life. His tragic life, however, turns to catastrophe when he becomes a lover of Joanna Burden, a white spinster in her early forties, who is also a childhood trauma victim. When she forces him to act as a black man and to pray with her, Christmas kills her because her demand not only denies his 30 years of conflict but also triggers his racial and religious trauma and makes him outraged. He is also killed as a black man in the end.