"One of the essential teachings that Trungpa propagated in America is that of “nontheism,” which he considered an aspect of egolessness. Reduced to its pith, nontheism is the teaching that intervention of ultimate reality, whether called God or by some other name, is not the source of salvation for us beings of the temporal world. Rather, we must make our own salvation, helpedperhaps by more realized beings, such as Christ or Buddha or saints or the guru, but basically alone, reliant on our own wit and grit. No God or external Power will intervene for us, or condemn us.
"The consequences of rejecting or accepting the principle of salvation-through-God are far-reaching. For example: the power of sin and guilt may be much less for a Buddhist, who does not accept such salvation. And the power of prayer and self-surrender may be greatly enhanced for a Christian, who does. In general, Buddhists do not use the name God to describe the ultimate. But I believe it is important that this not be seen as a denial of Christians’ experience or belief. For practical purposes, nontheism is better understood as a method rather than as a creed.
"Nontheism is not a dictionary word but a word Trungpa created to express the Buddhist viewpoint. It is quite different from atheism; Buddhism neither denies nor asserts the existence of God. Nor is nontheism agnosticism, meaning the belief that it is not possible to know ultimate truths. Buddhism asserts that it is possible to know the ultimate through direct meditative perception. (Albeit not through intellect and logic; all “proofs of God” are held to be fallacious.) Nontheism is simply the Buddhist teaching that salvationism might eventually lead to spiritual obstacles: perhaps resentment towards God—or doubt towards one’s own worthiness—in the face of strong adversity. Perhaps, more subtly, it may be a tendency to see “someone else” as responsible for the general well-being of oneself and the world. And from there might arise a whole subconscious system of helplessness, entitlement and blame."
from: A Nontheist's Journey By Rob Lee, writing about Trungpa Rinpoche's ideas