Pop singer Katy Perry, who once sung Christian music, faces a law suit by a group of Christian musicians for allegedly stealing their song and polluting it with what they call "black magic."

Grammy-nominated rapper Flame (Marcus Gray), Chike Ojukwu, Emanuel Lambert and Grammy-winning rapper LeCrae (Lecrae Moore) - filed a lawsuit in St. Louis federal court Tuesday against the pop star and Capitol Records, the St. Louis-Post Dispatch newspaper reports.

This is part of an ongoing saga in which Perry has come under fire from both Christians and Muslims for what her music expresses.

The Christian musicians claim that Perry and her co-writers infringed the copyright of their song Joyful Noise for Perry's Dark Horse.

Joyful Noise has been "irreparably tarnished by its association with the witchcraft, paganism, black magic, and Illuminati imagery evoked by the same music in Dark Horse," they said.

In February a pendant bearing the word "Allah" has been removed from Perry's "Dark Horse" video, after a petition on Change.org. Shazad Iqbal, the U.K. resident who wrote the complaint, said the clip was "highly controversial" due to its "portrayal of blasphemy."

Iqbal claimed in an interview with Rolling Stone magazine, that at the video's 1:15 mark, a man wearing the pendant is burned.

"Such goes to show, that blasphemy is clearly conveyed in the video, since Katy Perry (who appears to be representing an opposition of God) engulfs the believer and the word God in flames," the petition said.

"This is the reason for lodging the petition, so that people from different walks of life, different religions and from different parts of the world, agree that the video promotes blasphemy, using the name of God in an irrelevant and distasteful manner would be considered inappropriate by any religion."

Joyful Noise was written in 2007 and released in 2008. The song received a 2008 Gospel Music Association Dove Award nomination for the best rap/hip-hop song, the suit says.

The album, "Our World: Redeemed," received a Grammy Award nomination for best rock or rap gospel album and a Stellar Award nomination for rap album of the year in 2008.

The musicians said that Perry not only hijacked their music but also destroyed their reputation in the Christian music world. Seemingly, because of Perry's Dark Horse video, they are now associated with the anti-Christian witchcraft and imagery, TMZ reported.

Katy Perry, born Katy Hudson, was raised by two Pentecostal pastors and was discovered by Nashville producers while singing in a church.

Hudson incorporated primarily Christian rock and contemporary Christian music elements in her compositions, with lyrical themes of adolescence revolving around faith in God.