One way of responding is to look at results.

Naturalists (and atheists/seculars) are no more likely than believers to be criminals or cheats. Many are kind and giving and live exemplary lives. It is not just possible, but common, for people to be “good without God”.

Another is to recognize that values have a solid basis, separate from a presumed presence or role of God.

Part of this appears to be genetic, as in mothers caring for their children. Aspects of this can also be seen in some non-human species. Kindness, sharing, and other virtues are innate parts of human nature and, from an evolutionary perspective, it can easily be seen that groups whose members cooperate would have had an advantage over those who did not, and that these traits would be passed on.

Another part is social and learned, where a culture’s rules are taught to children, encouraged in schools, and enforced by peer pressure and law.

The main values of naturalists are seen in the customs and laws of their communities. Anthropologists have shown that these are similar in cultures around the world. All cultures value kindness, love, respect for others, seeking wisdom, perseverance, justice, and forgiveness. All have rules against murder, lying, incest, and theft. The Golden Rule is present, with different wording, in all major religious traditions.

Basis for values

Where believers feel that values are given by God, naturalists see values as grounded in nature. This begins at the simplest levels, where all creatures distinguish good from bad. Be it a single-celled amoeba or a plant, insect, reptile, or mammal, all are attracted to things that are good for them and avoid things that cause harm. A central principle and value lies behind this, in maintaining life and well-being.

Since humans are social creatures, this principle and value has two perspectives. One is individual, in acting in ways that are good for one’s own emotional and material well-being. The other pertains to groups where, as group harmony is desired, self-interest is constrained and behaviors like kindness and cooperation are valued. A tension often exists between self-interest and the good of the group (and, also, between the good of a small sub-group and the good of a larger group), and this accounts for many challenges and problems. Given a range of tendencies in individuals (in being selfish or selfless, in varying degrees and in different settings), groups tend to encourage and reward choices that contribute to the well-being of the group.

Comparison with traditional religion

Naturalist values are largely the same as those in Judeo-Christian tradition. Nothing unusual or worrisome is advocated. And, contrary to a misconception and false accusation, while a naturalist view recognizes “survival of the fittest” as a process in nature, it does not recommend this as a model for human behavior.

But while values are largely similar, some differences in emphasis can be seen.

One example is levels of respect for things that are looked to as sources of wisdom and truth.

Believers show greater respect for biblical writings and religious authorities, while a naturalist respect for science includes regular challenge to tradition, and claims may be rejected and practices are more willingly changed based on what best fits with available evidence.

Another example is that a naturalist focus on nature may include greater emphasis on ecology.

Environmental concern is also prominent in religions (with a mandate, in Judeo-Christian doctrine, of stewardship for the Earth). But, in traditions that see this world as a way-station to a greater and eternal world in heaven, concern may be less urgent than in a naturalist view that sees this world as all there is.

Links to full articles and web pages
Steven Pinker. The Moral Instinct. New York Times. 2008.
Frans de Waal. Morals without God. 2011.
Rights from Wrongs. Review of book by Alan Derschowitz.
Virtues and Vices

Additional reading 
Donald Crosby. A Religion of Nature. SUNY Press. 2002. (Values in Nature, pages 74-86)
Patricia Churchland. Braintrust: What Neuroscience Tells Us about Morality. Princeton University Press. 2011.
Frans de Waal. Primates and Philosophers: How Morality Evolved. Princeton University Press. 2009.
Frans de Waal. Good Natured: The Origin of Right and Wrong in Primates and Other Animals. Princeton University Press. 1997.
Frans de Waal. The Age of Empathy. Crown. 2009.
Jonathan Haidt. The Righteous Mind: Why Good People are Divided by Politics and Religion. Pantheon Books. NY. 2012.
Loyal Rue. Everyone’s Story. SUNY Press. 2000. (Chapter 4: What matters ultimately?, pages 99-108).
Jeffrey Moses, Oneness: Great Principles Shared by All Religions. Ballentine Books. 2002.