The springs of the truest prayer and the deepest poetry, twin expressions of our outward-going passion for that Eternity which is our home, rise very near together in the heart.
~ by Evelyn Underhill
Dom Henri le Saux, a French Benedictine monk, suggests that the sacred sound "OM" can be used by anyone:
More than any particular name of Divinity, OM conveys the ineffability and the depths of the divine Mystery. It bears no distinct meaning ... It does not even recall any mythological or semi-historic event. It is a kind of inarticulate exclamation uttered when you are confronted with the Presence in yourself and around yourself.
You could say that OM is a name of God which is not a name.