You could see religion as a sort of complex system, with myths, moral & symbolic codes, codified worship behaviors (i.e., rituals), and creation-and-destruction narratives. Religions are extremely successful because they give purpose, and meaning to life.
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From the point of view of belief:
Theism, is the belief that some sort of personal God exists and HE is involved with the universe.
Agnosticism: The truth about certain religious claims, is unknowable.
Deism: There is a God but this supreme being does not intervene in human affairs. Deists typically reject supernatural events such as prophecy and miracles.
Monotheism: The belief that there is only one God.
Pantheism: God is the summation of the all universe. God = Nature.
Transtheism: A system of philosophy which is neither theistic, nor atheistic. Paul Tillich writes:
The courage to take meaninglessness into itself presupposes a relation to the ground of being which we have called "absolute faith." It is without a special content, yet it is not without content. The content of absolute faith is the "god above God." Absolute faith and its consequence, the courage that takes the radical doubt, the doubt about God, into itself, transcends the theistic idea of God.Fideism: It maintains that faith is independent of reason. Tertulian's Credo quia absurdum.
