De-fibrillation killed him. A church that size probably already has an AED and I doubt it took EMS 40 minutes to get there. They probably worked with him that long . He had Drs there. They could do anything an ER could at that point, most likely. He was probably flat lined.
A question, did they check the mike and baptismal to verify that yes, there was an electrical potential? Maybe he actually had a heart attack.