So is God still relevant to ethics?

God is the ultimate principle of Spinoza's Ethics as is so for all ethics in Jewish, Muslim, Christian, and other monotheistic traditions. The scholastic philosophers, influenced by Augustine interpreting Plato and the Islamic philosophers commenting on Aristotle, taught that God as Supreme Being is the Summum Bonum, the first and final cause of all beings and therefore the End of all creation including human behavior.

"Being" and "beings" are concepts (metaphors) in the Western ontological tradition ("ontology"=study of being).  God as Being and creatures as beings is a part of that tradition which often speaks of God as a super-being, an infinite projection of the highest and best qualities of creation.

Spinoza's God was not above or outside Nature as was so in more orthodox traditions. Many commentators interpret Spinoza's God as identified with Nature, not with the parts but the Whole which is in and guiding all the parts.  Love of God is the highest act of human ethics.

When Einstein was asked if he believed in God ("God does not roll dice!") and referred to Spinoza's, he was probably saying that Reality, the Universe, or Nature as a Whole is bigger than the sum of its parts. When Stephen Hawking talked about "seeing into the mind of God," he said he was talking metaphorically about achieving the Unified Theory of Everything in science.  Telihard de Chardin, the Jesuit paleontologist and poet, speaks of the Omega Point (as does physicist David Deutsch) towards which the universe, including humanity, is evolving, when and where everything comes together in the fullness of consciousness. Alfred North Whitehead's God is a Becoming Whole of all that exists, the relational process we in our science and art and all our activities are trying to achieve.

In the History of God (see Karen Armstrong), the gods that arose in a more tribal hunter-gathering culture were symbols of unexplained powerful forces in nature and in society. In the turn to agriculture when tribes came together to form civilizations, often a chief god (that of the dominating tribe) was worshipped. Then came nation-states and empires for expanding and controlling commerce and One God (or in some Eastern traditions One Way, Spirit). Now as we approach Global and Universal dimensions, may the Force be with you.

So to our question: Is God necessary for a contemporary theory of ethics? The answer of course is no and yes--just what you would expect from a wishy-washy dialectical thinker.

No.  It is quite sufficient to build an ethics on the transcending nature of humanity.  I think my model relying on evidence from neuroscience and evolutionary psychology can adequately indicate right and wrong, good and evil behavior beyond relative moralities.

In fact I think that God can be downright harmful to an ethics if it is used to support polarized (as opposed to tensional or dialectical) thinking.  It can split the world and all of us into the Righteous against Sinners, the Pure as the White snow and the Impure Colored, the Included Saved and the Excluded Damned.  This God thinking leads to a hierarchy in personal dignity or holiness, rejection of certain groups, violence justified by dehumanization, narrow self-interest over mutual interests, anti-intellectualism, no salvation outside my church, absolute tyranny and infallibility on the part of those who claim a direct line to the Absolute.

Yes.  God-talk recognizes the role of metaphor and imagination in our pursuit of truth and fulfillment. It can be an affirmation of our presence now in a relational, limited, transcending adaptation to our universe by expressing metaphorically our eternal and infinite stretch between Alpha and Omega, Mind and Matter, Personality and Communality, Determined and Freedom, Real and Ideal. The time, the place, the community that is not-yet and is the motivation for the survival and transcendence of our humanity.

But again, not if God is the Man in the Sky (see the movie "The Invention of Lying") or a Super Man or Paternalistic Autocrat or Punishing Father or some Entity above and beyond nature that again reenforces exclusion, division, violence, and ignorance.

God is Love, says St. John. If you live in love, you live in God and God in you. So maybe if we really get a handle on love, we can let God go. Let's see if that might work later.