One idea would be that religion is a means of validating and universalizing beliefs regarding how people should govern themselves--and secondarily (to a greater or lesser extent among different religions) the governance of society. Ideologies do the same thing, but emphasize the governance of society. Both theologies and ideologies are based on beliefs, and beliefs are validated by being claimed: holding a belief, whether sacral/theological or secular/ideological, makes it true for the believer.