Re: Thinking of taking aikido!
According to Islam, when praying, there should be nothing between you and God. To me, that is the same as clearing my head of all disturbances, or calming the mind if you will. Muslims are often amazed to learn that Buddhist meditation is not worship of the Buddha himself, but a spiritual practice much like their own. There is no direct concept of God in zen, but trying to attune oneself to the wholeness is pretty much the same in my book.
The only real difference in worship lies in the doctrines.
Although there certainly is a difference in how monks pray and how layman christians pray. I also think it may differ between different branches of christianity. In any case, I think the purpouse is the same, and the desired effect is the same.