What is a “nontheistic spiritual humanist” ? Let me break it down for you, as Kathy Griffin would say.
Nontheistic is not the same as Atheist. Atheism is the active belief that there is no god(s). Most atheists believe, instead, in the supremacy of the ‘scientific method’ to explain reality. They generally insist on a ‘rational worldview’ and reject all things ‘spiritual’. Atheism is the opposite of ‘theism’ – the belief in one or more dieties. That term is first known to have been used by Ralph Cudworth (1617–88) who wrote that theists “affirm that a perfectly conscious understanding being, or mind, existing of itself from eternity, was the cause of all other things” 
Nor am I a ‘deist’ – someone who believes this world was created or initiated by one or more dieties who then stepped back and do(es) not actively participate in this reality. Such god(s) do not answer prayers, punish non-believers or appear to prophets. Many of the US ‘founding fathers’ have been described as ‘deists’ – although it may some were atheists who were afraid of coming out as such in their time and place.
A ‘nontheist’ does not believe in the existence of active or passive dieties, although without the atheist’s typical rejection of any spiritual reality.
Humanism, although often confalted with atheism, is not identical to it. There is no official Statement of Faith that one must swear to as a Humanist, but the Humanist Institute considers the following as “core humanist principles”. They also state this is not dogma and not every self-professed Humanist subscribes to every word although they do represent a broad consensus:
- Science and Reason: The most reliable means of obtaining knowledge is through the application of the scientific method, critical evaluation, and reasoned analysis;
- Human Rights: An affirmation of the worth, dignity and autonomy of the individual, including the freedom of conscience, thought, association, speech, and religion;
- Democracy: Democratic forms of government provide the best means of ensuring self-determination;
- Tolerance: Separation of church and state, freedom from religion, and freedom of conscience;
- Non-theism: Morality is an intrinsic part of human nature and does not depend upon external forces or divine mandate; humans must act responsibly toward one another, toward future generations, and toward the natural world;
- Enrichment: Provision for the personal enrichment and development of humanity through art, literature, and music;
- Universality: Humanism is a philosophy that applies to all human beings, independent of political borders.
While not all Humanists are atheists, there is general agreement that regardless of spiritual orientation, to be Humanist is to reject dogma and ‘divine instruction’ in matters of ethics. We must accept responsibility for our own choices without blaming a deity, vision or ‘holy writing’. As Unitarian/Universalist Minister Kenneth Phifer expressed it: “Humanism tells us that whatever our philosophy of the universe may be, ultimately the responsibility for the kind of world in which we live rests with us.”
And so, while we utilize imagery of gods from various cultures and religious traditions, we recognize such gods as allegorical. At the same time, they are more than just stories that illustrate foilables of humans past and present. We view them as our best attempts at representing a spiritual reality that is neither quantifiable by, nor reducible to, a modern scientific approach.
A truly open scientific mind will see how ‘quantum physics’ contradicted known and accepted scientific theories last century and be open to the possibility of yet another new paradigm to arise. Robert Lanza illustrates how much damage quantum physics has done to earlier scientific theories of existence and posits a new world view. The publisher’s publicity for his book Biocentism includes the following description: “Biocentrism completes this shift in worldview, turning the planet upside down again with the revolutionary view that life creates the universe instead of the other way around. In this new paradigm, life is not just an accidental byproduct of the laws of physics.”
 Cudworth, Ralph. The True Intellectual System of the Universe, Vol. I. 1678 (reprinted by Gould & Newman, 1837)
 Lanza, Robert. Biocentrism: How Life and Consciousness are the Keys to Understanding the True Nature of the Universe 2010