The 'Firework' singer, who is the daughter of two evangelist pastors, told Grazia magazine that the controversial comedian has a strong spiritual belief system.
"Russell has changed his life and wants to help other people change theirs. For all his naughtiness on the surface, underneath he's truly good," she said. "My parents adore him."
The musician added: "People laugh when I say Russell is a man of God but I'm just waiting for them to see what he does."
Perry also revealed that the couple have plans to establish their own charity to benefit the less fortunate.
The star noted: "We have this plan to set up a foundation to help people: feed them, clothe them, give shelter. We don't want to use our fame just to sit on our money on a mountain, we want to do something with it."
Earlier this week, Perry revealed that she and Brand are planning to embark on a Christmas "experience".