The Children of God was a religious movement founded in 1968 by, former pastor, David Brandt Berg. Berg promoted unbelievable and dangerous ideologies, saying that it was the way God intended for humans to live. He promoted widespread promiscuity and child brides through many propaganda posters (as shown below) He also scored a extremely high score on the qualifications of having NPD. 

As this movement developed, Berg rised to a cult-leader status. In lots of ways, could be a narcissist's dream. To be the centre of obedient followers fulfills their need for admiration and control and gives them many opportunities to exploit people. Religion is tailor made for their fantasies to fit their needs, and gives them a chance to be like God.

What Berg Said

Berg told his faithful followers that he was called by God (somewhat like a prophet) to spread His word. He told them that he was the mouthpiece of God. Some thought his ideas were ludicrous, but he convinced them that only him, the chosen one, had the intellectual capacity and wisdom to understand what God wanted, placing himself above all others. 

With a cult, bad beliefs can be spread through the unquestioning followers and they usually end in a tragic mass suicide. This is a perfect example of how narcissism can get wildly and dangerously out of hand.