I ran across a blog this morning by "Orthodox Monk" in which the author recommends that Pentecostals not practice the Jesus Prayer because it may be spiritually dangerous. On the one hand, I agree that practicing the Jesus Prayer is dangerous--for anyone, especially someone who is not under the guidance of a spiritual father who has spent years practicing (himself under the guidance of a spiritual father) the prayer. The greatest danger with any spiritual practice is delusion: one can think he or she is practicing prayer at a "level" (Oh how I despise that concept when it comes to spiritual matters!) deeper, greater, more profound, etc. than they really are.
On the other hand, spiritual practice, perhaps particularly the Jesus Prayer, is also a path by which one may be delivered from delusion. How else might one be enlightened to his own delusion than by calling on the Name of Jesus? It is an irony, like most of the spiritual life.
My recommendation to anyone who might stumble across this blog is to simply pray and pray simply. As a Pentecostal, I began "saying" the Jesus Prayer (what is and isn't prayer I leave in God's hands). At first it was something I mixed with "praying in tongues." But gradually, my heart was lifted and my mind focused through the Jesus Prayer so that I "prayed in tongues" less and less. The kind of prayer beyond words (groanings too deep to be uttered, a la Romans 8:26?) that "praying in tongues" seemed to provide for me was eclipsed by the Jesus Prayer. Actually, the metaphor is more like a faint star disappearing as the sun rises.
What I was actually doing when I was "praying in tongues," I do not know. God knows. My heart was crying out to Him and somehow He heard my cry and has led me to the Safe Haven of His Church.
If you would like to say the Jesus Prayer, do so simply. And God in His mercy will hear the cry of your heart.