The eye in the sky, and the judgement in the afterlife, are the ultimate police force. All the more so because they are not just in the sky or in the afterlife, they become interiorized as a part of our personality structure, the super-ego Freud wrote about. It's such a handy and effective way to manufacture acquiescent and cooperative social subjects that one can only marvel that it needed so many millennia in order to be perfected.
This is by way of commentary to an interview on social and religious evolution by Joseph Henrich ("Conversations with Tyler", audio).
This interiorized god as a personification of social values was theorized (albeit in an implicit way) by George Herbert Mead in his notion of the "generalized other." And, earlier still, by Adam Smith with his notion of the "impartial spectator." More about Smith's interiorized sociality here (in Spanish).