Complex sentence: Among Eastern Christians belief in witchcraft was regarded as "deisdemonia"-superstition-and by the 9th and 10th centuries in the West, belief in witchcraft had begun to be seen as heresy.
Split into simpler sentences: Among Eastern Christians belief in witchcraft was regarded as "deisdemonia"--superstition. In the West, however, by the 9th and 10th centuries, belief in witchcraft began to be seen as heresy.