Actually "channeling" is thought of as "possession" by most Christian churches and some other religions. Think about it...would you invite anyone living into your mind and allow them to speak through you?
For a very good example of the dangers, I refer you to two current Moonies, who finally caught on to the Zimbabwian who supposedly "channeled" Moon's son,
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"Cults," Sects, and "New Religious Movements"