During the late 1940's and well into the 1950's Charles Templeton was one of the leading evangelists in North America. He was a contemporary and close friend of Billy Graham and even travelled and roomed with him on joint crusades. Some, at the time, regarded him as a greater evangelist than Graham himself. In 1957, just following his greatest crusade ever, and after a long period of soul searching, he turned his back on his ministry and walked away from it. He said to himself, in effect, “how can I stand here and preach passionately to these people when I know that I am not preaching the truth.”
He wrote in “Farewell to God” --- “According to Christian theology, God is omniscient and exists apart from time. Being omniscient he knows the end from the beginning. But if true, would this not mean that all temporal life is predetermined? If God knows the end from the beginning then nothing is subject to change --- otherwise it would not have been known from the beginning. This being so, prayer cannot possibly change anything and there is no point to it. Apart from its function as worship, prayer is based on the premise that God can be talked into running the universe according to the wishes of a devout person on his knees. But, again, try to imagine the chaos if every devout person's prayers were answered! Belief in the efficacy of prayer is a form of self-delusion. Our real prayers are not what we say while on our knees --- the facile words whispered during a prayer. They are the aspirations, attitudes, and desires that motivate our daily lives. It is easy to prime the pump and have the words gush forth in a torrent of pious phrases but the proof of what we really want, regardless of what we say we want, is evident in the way we live. “