Culture is an evolutionary strategy, and values must be judged by the consequences of the kind of behaviours they encourage.
It doesn't matter wether the belief is religious or secular, and indeed, students of the history of religion often speak of the religious nature of secular thought. Nor is there a difference between religious and secular thinking at the neurophysiological level. I posted this to someone elses blog a while ago but the blog owner didn't find it relevant enough to post. It contains some material that might be relevant here.
1.
I think its worth asking what religious and secular ethics even mean in the first place, when students of religion cannot even define the religious and the secular as different categories that can be usefully applied across all cultures. (In a similar way, students of comparative philosophy have similar hermaneutic problems when they try to apply labels of culture-specific origin such as epistemology to other societies.) Secondly there exists the bigger problem that students of comparative religion such as Mircea Eliade have demonstrated the presence of mythological and 'religious' thinking within mainstream 'secular' thought such as Marxism, American patriotism and also Neitzsche's ideal of the Superman which has been interpreted as a justification of present action on its not-yet-present behalf. Indeed, it has also been said that all of modern secular politics represents socioeconomic messianism of some kind of another.
In keeping with the observations that there is no objective difference between the religious and the secular, is that there exist no specific parts of the brain that have an exclusively 'religious' or 'secular' functioning. Indeed, there is evidence that the differences in brain structure that separate liberals from conservatives in an American context are of more importance than those separating religious and secular thought, although Conservatives are more likely to be religious.
2.
As for the rationality of atheistic or secular morality, we should be careful to remember that moral values are not components of phenomena themselves, but are merely products of the observers own cognition and therefore exist only in perception. Moral judgments therefore constitute mistaken attempts to describe the nature of phenomena, and there can be no moral knowledge because the word 'knowledge' implies an understanding of the actual nature of phenomena, rather than unsubstantiated perceptions of them. But in spite of the irrefutable logic of error theory, most atheists and other self proclaimed 'rationalists' are not meta-ethical nihilists. It is like people will refute illogic they don't like and then keep clinging to the rest.
This observation actually relates to my first observation, because of course in Western bioethics there is an obsession with 'conciousness' and 'personhood' that can trace its origins to the Christian and especially Protestant ideal of the individual soul, so that the ideal of finding a point in human ontology when a fetus becomes a 'human being' based upon awareness is nothing more than a secular revaluation of the rationally refuted concept of quickening. Likewise most secularists are moral universalists, who support Enlightenment concepts such as human rights and merely disagree between themselves about the proper way to achieve a goal of universal suffrage, but this moral universalism is a part of their culture-specific Christian heritage.
3.
New Atheists like to claim that religion is a costly spandrel or a mind-virus (although they have to justify this position by resorting to selection bias). And politicised secularists actually make one-sided, moralistic arguments against the historical 'crimes' of religion so frequently, that their ridiculous claims that religion is purely costly and harmful (despite being so successful for centuries!) are obviously an example of the 'ought-is' or moralistic logical fallacy.
But it is through morals that religion (and other ideologies) control people. What if the capacity for moral judgement itself is a useless and costly spandrel? Many of the 'crimes' that were perpetrated by organised religions or that were justified using religious arguments, were ultimately in the genetic self-interest of the perpetrator.
We should remember that according to Satoshi Kanazawa, the secular left are more likely than the religious right to argue using the moralistic fallacy, as can be seen by their reliance upon accusations involving -isms and -phobias, as well as the leftist nature of the 'sociobiology wars' etc.
4.
We should also remember that to appeal to novelty is a logical fallacy, just as is appeal to tradition. And the widespread secular support for policies such as pro-choice and gay marriage is obviously based on the appeal of novelty, given how few of the average policy-supporters actually understand the issues in question. Far from being proof of secular rationality, the fact that certain political positions are so popular among secularists who haven't considered the issues actually confirms that the average secularist is a herd animal, who is either incapable of making his own decisions about social issues or is too spineless to go against the herd so he still follows it anyway, even if it takes him off the side of a cliff. In other words, secularists are vulnerable to the same forms of social control as the religious are.
Although secular ethics are almost always universalist, I notice that secular types prefer to ignore inconvenient universals, such as the universality of some kind of family values, that all cultures associate womanhood with childbirth and childrearing, or that heterosexual marriage is universal whilst homosexual marriage is not. Of course conservative ethics are frequently nonsensical, but so are moralistic, secular statements such as "marriage is about love, not the family!" and "women do not exist simply to have babies", once one takes into account the implications of sociobiology for humans, or of functionalism in anthropology.
Despite the efforts of secular humanists to dismiss matters of sex as socially irrelevant, the fact is that all cultures possess taboos and laws about sexual behaviour that universally support the heterosexual family. In ancient Greece homosexuality was widely practiced, tolerated and according to correct social context, encouraged. Yet these men were still expected to have heterosexual families, and homosexual marriage was unheard of. I shouldn't need to point out the biological explanation why heterosexuality alone was favoured in Greek marriage customs, or why some cultures have completely condemned and persecuted homosexuals with no ill-effect to the survival of the group at large, although no cultures have ever persecuted heterosexuals in the same way. Of course matters of sexual behaviour are not socially irrelevant, and anyone who thinks that they are, is extremely ignorant of anthropology.
Another logical fallacy is the 'fallacists fallacy', which is the fallacy by which things are considered to be irrational because they have been rationalised. But humans always rationalise things, and all that matters is the usefulness of the rationalisation in promoting behaviour. As cultural beliefs are subject to natural selection, it is not the rationalisation itself but its outcomes that must be judged as rational, and religious taboos and preferences that are widely practiced across cultures and over centuries are therefore tried and tested as practical. In contrast to this vast body of accumulated practical experience, much of secular ethics comes accross as children throwing toys out of their pram.