Brutal torture of dissidents and consolidation of wealth played a role for most revolutionary groups, but at the onset of the revolution in 1979 most groups were not looking for a theocracy.

The Tudeh and Fedaian were more important in finishing off the government than theocracy supporters, and even the powerful People's Mujahedin (which was Islamist) did not want a theocracy.

See: https://en.wikipedia.org/wiki/Iranian_Revolution#Opposition_...