The Church of Scientology (search) may be feeling a little less shook up these days, now that Priscilla Presley's (search) teenage son has formally joined the religion.

Navarone Garibaldi (search), who'd been smoking pot and had hallucinogenic mushrooms with him when he was pulled over for speeding last year in L.A., has completed the church's "student volunteer minister course."

The summer-course completion marks Garibaldi's first foray into the teachings of Scientology, sources say. Mom Presley, 60, has been a devotee for decades.

Church officials were furious about a "Celebrity Justice" report of then-17-year-old Garibaldi's drug use after police in Glendale, Calif., hauled him off to the jailhouse.

Part of the belief system is that humans are infested with the souls of dead space aliens who were brought to Earth 75 million years ago.