Complex sentence: It was the first long autobiographical work to appear in underground comics, and was extremely personal, detailing Green's childhood struggle with a disorder which in Catholicism is referred to as scrupulosity, and was later diagnosed as obsessive-compulsive disorder (OCD).
Split into simpler sentences: It was the first long autobiographical work to appear in underground comix, and was extremely personal, detailing Green's childhood struggle with a disorder where he refers to Catholicism as scrupulosity. Green was later diagnosed as obsessive-compulsive disorder (OCD).