Rather than type the LONG story
, here's a link to Jeremy's bio here on the Penguin.
Well, ok...here's the section that applies:
Two weeks into their tour to support the album, in L.A., Jeremy disappeared. He had left the hotel at about 3:00 to visit a bookstore on Hollywood Blvd, and on the street he was approached by a member of the religious group called The Children Of God. When the guitarist failed to show up for that evening's gig, the police were contacted, and five worry-filled days later Spencer was traced to the Children Of God headquarters, a warehouse in downtown L.A. In order to get in to see Spencer, manager Clifford Davis had to make up a story about Jeremy's wife, Fiona, being seriously ill. According to a Fleetwood Mac roadie who was at the scene, Spencer "was walking around in a daze like a zombie...he'd been brainwashed. It nearly killed me to see him." His head had been shaved and he now answered to the biblical name Jonathan. Davis and Spencer talked for 3 hours, while members of the cult rubbed Jeremy's arms and chanted 'Jesus Loves You' repeatedly. Apparently the guitarist had been doing some 'soul-searching': "Acid trips and dope, fame and fortune, pride and conceit, idleness and every other sin took hold of me from the start of the material success of the band." Much like Peter Green, Jeremy also felt unworthy of all the adoration he'd been receiving in the group. Ironically, to replace Spencer on their tour, which still had 6 weeks left, Fleetwood Mac begged Green to fly in and help them complete the shows, which he did.
Jeremy Spencer Bio at The Penguin
In Mick's book, he says that on the plane from San Francisco to LA, Jeremy had what I would describe as a mild panic attack about going to Los Angeles. It was not too long after the San Fernando Valley earthquake in 1971 which caused some MAJOR damage in the area. Jeremy (again, according to Mick's book) took it as some sort of evil "omen".
1971 San Fernando Earthquake