Divination is crucial to most forms of polytheism. Consider what the word means: "divination" is derived form "divine". To practice divination is to ask the gods for advice and guidance. The ancients all practices it, as do modern African, Chinese, and American polytheists.
To the Christians, I'd say that if your god "knows all things", isn't he a bit selfish keeping it all to himself? I was amused to read the condemnation of astrology in the current Catholic catechism, where the writer said that trying to foresee the future is showing distrust in providence: I hope he was careful not to hear the weather forecast…