John Ramirez once worshipped the devil and carried out evil in the name of Satan.
Now a pastor, he knows all about the dark side.
He once sacrificed animals as part of satanic rituals and his friends even called him, "Lucifer's son."
In his book, Armed and Dangerous: The Ultimate Battle Plan for Targeting and Defeating the Enemy, Ramirez details why Christians need to pray more effectively.
"I wrote this book because I wanted Christians to know that it's not only a defense spiritual warfare, but there's an offense spiritual warfare," he told CBN News. "We need to keep the devil, the devil in his place."
Watch CBN News anchor Charlene Aaron's interview with Ramirez on Prayer Link
Ramirez said he was most effective in Satanism when believers were prayerless.
"I was able to go in there and capitalize and take a stand and a position in the spirit realm against the Christians that were not praying," he explained. "I took that territory away so I owned your neighbor; I owned your neighborhood; I owned your region because you didn't saturate with prayers. I beat you to it."
He also shared how when Christians did pray that it stopped his evil plans in their tracks.
"It is those believers, it's that group of people, those intercessors that gave me such a beatdown in the spiritual," he said. "When I came into the neighborhood and they were in the spirit together holding hands. Do I know they were physically holding hands in one area? I don't know, but in the spirit realm, they were holding hands. And, they were able to chase me out the neighborhood. No mission accomplished. Mission aborted, weakened my assignment and no mission accomplished because they knew something: they had the power in that neighborhood that I didn't have."
Ramirez now encourages Christians to broaden their prayers and to be sensitive to pray for the nation, schools and other areas.
He said, "If I know what's going on in my neighborhood, then I know what to lift up to the altar of God. And I think a lot of times we miss it because we have been called to be intercessors between life and death. We need to intercede for our neighborhood, our region, then our family, our loved ones, our husbands, wives, our workplaces."
After serving the devil for most of his life, he says that he wouldn't trade anything for what he's found in Christ.
"For twenty-five years of my life, I was able to do anything to anybody, anywhere," said Ramirez. "I count that all to be foolish to gain Christ. He's my Uno. He's the breath that I breathe. He walks with me. I can hear the sound of His voice in my ear."
See more of John Ramirez' testimony below: