Religion ought to be a prime target on International Women's Day. Say what you like about global capitalism, or "the patriarchy", is there any force more potent than organised religion when it comes to putting women in their place and keeping them there? Whether it's the campaign by the Catholic church in America to restrict access to contraception in the name of "religious freedom", ultra-Orthodox Jews screaming obscene abuse at little girls going to school, efforts by traditionalist-minded Anglicans to maintain the glass ceiling when it comes to episcopal appointments, or the latest horror story from Afghanistan, religion seems predicated on the assumption that women are inferior to men and can only find fulfilment and security by accepting their secondary position in the divine scheme of things.

Yet because of the prevailing public etiquette that says that religious views should be accorded particular respect, and sometimes legal privilege, religion as such is rarely called out for its underlying sexism. Instead culture gets the blame, or fundamentalism, or a patriarchal conspiracy that we are assured has taken control of religion and twisted it for its own ends.

Of course there are progressive, even feminist, voices within all the major religions. But they are historically novel and even today may struggle to get their voices heard. It's unlikely to be a coincidence that the most religiously observant countries tend to be those with the worst records when it comes to the position of women. Or that the most secular and least religious countries score highest in terms of sexual equality.

Religion, almost every religion, views women primarily in terms of their biological function. It takes certain commonplace observations and draws from them conclusions that have restricted women's participation in society and undermined their sense of themselves. Because women bear children, religion has moralised about their sexual behaviour far more than about that of men, promoting in many societies a cult of chastity that has made women prisoners of their fathers and husbands. Because women tend to be smaller and less physically powerful than men, religion teaches them to defer to their husbands as they would to God ("for the husband is head of his wife as Christ is of the Church", as St Paul once charmingly put it). Because heterosexual men enjoy looking at women's bodies religion castigates sexually confident women as harlots and temptresses, inculcates shame and teaches that "modesty" requires covering up any part of themselves that some passing man might possibly find attractive.

It's true, of course, that time and social progress has eliminated some of the more grotesque examples of religiously-sponsored sexism. Hindu widows are no longer called upon to immolate themselves upon their husbands' funeral pyres (though social marginalisation often still awaits them instead). Spare daughters are no longer sent to live out their days in nunneries. Mainstream religious leaders are happy to deny that their faiths, when properly interpreted, are sexist at all. Who hasn't heard a Muslim apologist proclaim that Islam gave women property rights unknown in Europe until the 19th century, or a Christian point out the respect that Jesus showed to the women who were among his most prominent followers?

For that matter, at least in the west, women have long shown much higher levels of religiosity than have men. More women than men attend church every Sunday; women are more likely to pray and to express belief in God. Men are less likely to be interested in religion, and considerably more likely to be atheists. These factors are more pronounced in western, post-Christian societies where faith is no longer required for social conformity, suggesting that whatever it is that religion offers people (solace, community, hope for an afterlife or direct spiritual experience) appeals to women more than it does men.

Outside of the male-dominated priesthoods, it's women who traditionally passed on religious devotion within families and who often enforced communal religious norms. Men have often been bystanders in the misogynistic oppression of women, by women, in the name of religion or morality. Today, some of the loudest voices speaking out from a religious perspective against abortion -- something viewed by many feminists as a touchstone issue -- or in defence of traditional gender roles belong to women.

How to explain these apparent paradoxes? One answer might be that, historically, religion has protected women from some of the worst excesses of patriarchal societies. It instructed men to be faithful to their wives and to provide for their families. It condemned (usually) the worst excesses of domestic violence. Notwithstanding its exclusively male hierarchy, the Christian church has for most of European history been the only institution (with the possible exception of the brothel) that offered women independence, education, even power. A religious woman could be a scholar, a mystic, a poet, a businesswoman, the absolute ruler (subject only to the Pope) of her order, potentially a saint. A secular woman, unless a queen, could only be a wife.

Today, though, organised religion has been slow to take on board the notion of sexual equality. A woman might one day become President of the United States; it seems highly unlikely that a woman will ever become Pope. I wonder if the institutional sexism that religion has long displayed, and continues to display even in its least oppressive manifestations (such as the Anglican church) might somehow be a byproduct of its disproportionate appeal to women. Could it be, for example, that exclusively male priesthoods originated as a mechanism for ensuring male authority in an arena that would otherwise have been dominated by women?