If we're looking for a rationale other than "Loughner was nuts," I think the more relevant facts about him are that he was an atheist who detested religion and religious people, made lots of references to satanic New Age "conscience dreaming" (sic) and was involved in the occult.
When a fellow participant on a UFO website wrote a lengthy response to Loughner's question about "what is wrong or right with the current date?" which included the subordinate clause, "a day in Christ is as a thousand years," Loughner fixated on that one line, railing, "I won't listen to that fictitious crap without the author. This is laughable to notice a gospel or writing related to Christ."

"Mud Libel" (19 January 2011).