Matthew Murray, 24, posted the manifesto Sunday, putting it on a Web site for people who have abandoned organized churches, after the attack at Youth with a Mission in Arvada and before going to the New Life Church in Colorado Springs, The Denver Post reported Tuesday.
Much of the posting was taken word for word from a notebook left by Eric Harris, who killed 13 people with Dylan Klebold at Columbine High School in Littleton, Colo. Where Harris used the name of a classmate as an object of hate, Murray substituted "Christians."
Murray was 16 at the time of the Columbine attacks.
Jeanne Assam, a security guard at New Life, shot Murray. At a news conference Monday she said that when she saw Murray as the shooting started she knew she had been given "the assignment to end this before it got too much worse," CNN reported.
The church's pastor, the Rev. Brady Boyd, called Assam a hero. "She probably saved over a hundred lives," Boyd said. A coroner's report Tuesday said Murray died of a self-inflected gunshot wound and his death was a suicide, CNN said.