In America, both belief in god and religiosity are far more common among women than among men. Every survey ever done on Americans' belief in god or their religiosity shows this same difference, though the degree of difference between men and women does vary. The question everyone asks is: why? What's the reason for rates of belief in god and religiosity being higher with women than men?
A Gallup survey conducted May 5-8, 2011, asked "Do you believe in God" and "Do you believe in God or a Universal Spirit". The combined results were correlated to the sex of people responding (margin of error: +/- 4%):
National Average: 92%
Men: 90% Women: 94%
To be fair, the difference in belief in God between men and women is just within the margin of error. In theory, the rates of belief in God in 2011 could be virtually identical in men and women, but that's unlikely because the existence of a difference has been demonstrated so many times over many, many years.
And it's not just in America that this difference has been documented — it's been found in others nations as well. So while the difference here in this particular survey may be within the margin of error, it could also go in the opposite direction — belief among women could be as high as 98% while disbelief in men could be as low as 86%. Thus we can't use the margin of error here to conclude that the difference doesn't exist anymore.
Why Do Men and Women Believe at Different Rates?
Some of the difference between men and women is surely cultural. Even when men and women have he exact same experiences, they are going to interpret them differently and integrate those experiences into their lives in different ways. This is not necessarily due to anything biological, but simply because men and women are socialized differently, have different cultural expectations, and are treated differently by society.
It's no surprise that some have argued that these differences are ultimately biological and evolutionary in nature. There's at least superficial plausibility to the idea that if religion enhances social cohesion and kinship ties, then this would become either more appealing to women or would be something supported more widely among women.
On the other hand, so many evolutionary explanations of differences in how men and women think amount to little more than rationalizations for modern culture. If something enhances kinship ties we can imagine why there would be a biological impetus for women to be attracted to it, but we can't ignore all the ways in which women are socialized in that direction.
Perhaps the answer lies in religion itself. If religion is structured in ways designed to appeal to women, regardless of whether the reason for why its appealing is social or biological, then of course we'd see more women involved in religion. It would have to be something deep in the structure of religion, though, given how a variety of overt doctrines in many religions which shouldn't appeal to women — the masculinity of gods, the subordination of women, etc.
Differences Between Men & Women in Believing in God
The fact that we see differences in rates of belief in god across many nations suggests that the difference must be at least partially due to either some sort of inherent difference between men and women or something in religion itself (or both). But what might that difference be? Is there something about religion or theism that is more attractive to women? Is there something about men that makes them less receptive to theism or religion?