Contemplative Prayer - Very Dangerous
Richard Foster is a practicing Quaker, as such his theology focuses on silence rather than the written Word of God. Meditation - going deep within - to hear the 'voice' of God is what Quakerism is all about. Messages/thoughts in the silence have precedence over the doctrines in the Bible are readily accepted as 'new' revelation from God. Very, very dangerous. Stay away from contemplative prayer...it will lead to receiving messages from the unholy spirit world.
Mr. Yungen has thoroughly researched the various mystical practices of the 'new spirituality' that many evangelical churches have adopted. I recommend anything Ray Yungen writes on contemplative prayer as he has done his homework.