Religions teach mediatition through yoga, attaining emptyness. Prayer is also a form of mediation. The greatest difference between meditation and prayer is with one we seek nothingness, or being one with something, while with prayer we request an audience with God.
Without God as our focal point, we open ourselves up to the great deciever, Satan.
There is certainly danger everywhere, and most often we protect ourselves from falling by our own awareness and God's graciousness. But when we mediatate, if we don't understand the dangers, we present our souls, our self, to possession.
A primary truth: only two paths exist on this planet: one is Jesus Christ, the other is Satan. If you do not know Jesus Christ personally, you are in Satan's grasp. There is no other choice.
Any form of mediation without Jesus Christ as the center, the supreme protector of our soul, allows Satan entry to our self; allows possession of our body.
You see, prayer is meant to be our personal communion with God, Jesus Christ, and the Holy Spirit. When we pray seeking the trinity, the three that are one, God protects us from Satan. When we pray without God, we offer our self to Satan.
The bible makes it clear: Satan is the greatest deceiver man has ever known.