Because-

Sleeping Beastly asked, and Jordon has a great site:

jordan179 - Jonestown and its Place in a Larger Pattern:

"Jim Jones was an evangelical communist who became a minister to infiltrate the church with the gospel according to Marx and Lenin. He was an atheist missionary bringing his message of socialist redemption to the Christian heathen. 'I decided, how can I demonstrate my Marxism?,' remembered Jones of his days in 1950s Indiana. 'The thought was, infiltrate the church.' So in the forms of Pentecostal ritual, Jones smuggled socialism into the minds of true believers--who gradually became true believers of a different sort. Unless one counts his drug-induced bouts with self-messianism, Jones didn't believe in God."

Yes, the psycho-leader was communists/socialist; it wasn't your imagination.