But it does seem that way when you look at modern societies, particularly in the west - secularism often does appear to be the more progressive trend. Religious institutions are having to adapt, for example here in the UK the Church of England has recently agreed to women bishops.
Now we're talking. To add a finer point to this, it's really even more basic than conservative versus progressive views. It's rather about traditional, versus modern, versus postmodern value systems. That's the real benchmark. You have conservatives and progressives within each of those as well, if you think about it. You have fundamentalists within the traditionalist view that even make traditionalists wince, like Pat Robertson. You have fundamentalists within modernity that make many in modernity wince, like Richard Dawkins, and so forth.
To your point above, religions tend to be representative of the traditionalist value system. Religion always follows along behind supporting the culture its part of. Because of the sheer logistics of an institutional form of religion it is slow to adapt to changes in culture, but adapt it in fact does do. But conservatives within a culture are about putting the brakes on change, to halt a runaway effect where a society runs the risk of losing its sense of self identity and the support structures that keep it stable. Progressives are about pushing for needed change to adapt to changes in the landscape. They are necessary too to keep a culture from imploding in on itself as it becomes stagnant and unable to adapt to those changes in the environment.
Obviously religion is not conservative by default. If it were, Christianity or Buddhism or any other new emergent form of religious movement would never have been born! Christianity was like the hippie movement, pushing the boundaries away from traditionalist holdings, not about making more! But as within anything, it itself became a structure of a society and culture and the value systems of the culture took hold within it, and it's voice becomes the voice of the people with the officials at the top setting its tone.
I could go on, but I think you see my point. It would really behoove people to move beyond the debate about the 'rationality' of atheism and the 'silliness' of theism to the real issues. It's a little more complex and challenging to address than God versus No-God, but definitely more realistic and productive a discussion.