I've just noticed that that's the case for mainline Protestantism in general. Active members of PCUSA and ELCA congregations are right-leaning, even though the clergy of both voted strongly for Gore. The PCUSA, in particular, has a democratic structure and at the General Assembly, it was decided that gays can become pastors, that Arizona was to be boycotted because of their immigration policy etc.
Yet look at these figures:
Not really true. Although it is certainly the case that more active members of liberal mainline churches tend to be less liberal than their clergy, still studies show that two-thirds of Presbyterians, and about three-quarters of Episcopalians and Congregationalists are pro-choice on abortion, and sizeable majorities are liberal on other social issues as well. Since the 1960s and probably earlier surveys were finding more liberal and progressive social views associated with these groups. They were the strongest supporters of desegregation in the 50s and 60s and then the strongest proponents of the ERA in the 70s. Most of the Republican PCUSA and ECUSA people I've come across (including those involved in churches) are actually quite liberal on social issues. Theologically, these denominations are heavily skewed towards the liberal position as well: Pew surveys have found that less than 20% of members of Episcopal and Congregational churches believe in the literal truth of the Bible, while 40% believe it has no supernatural inspiration at all. Other surveys have found that these views have existed since the 1950s. Truth is, these denominations have always been among the best-educated and most intellectual groups in America, and that naturally leads to more progressive attitudes toward theology and social issues.
As far as "churchgoers being more conservative" in many of these denominations that isn't really much of an issue. Take for instance the local big, liberal Methodist church in my area. There isn't a whole lot of pressure to attend church regularly, as a result only the old people who grew up in Methodism their whole life will still be there faithfully every week. Younger people, families, etc. whose views tend to be more progressive will drop by casually every month or so. I read that in the Congregationalist church (for the purpose of this discussion I will use this term rather than UCC because UCC contains many non-Congregationalists) only about one-fifth of members consider themselves weekly attenders. In fact, in this denomination, it is considered "regular" attendance if you go once a month. So you can't necessarily say that because only old people still go to church weekly in liberal denominations, therefore practicing members of these denominations are more conservative. The standards necessary to be a "practicing" member are much looser.
And for those who say that the liberal denominations are no longer Republican: the Pew research center carried out a nation-wide survey of religious groups, which, although not perfect, is about the best source that we have to use for determining the US's religious landscape (it's called the Religious Landscape Survey in fact). The survey found that only 31% of mainline Presbyterians, 44% of UCC members (presumably higher among Congregationalists), and 45% of Episcopalians voted for Kerry in 2004. This would indicate that PCUSA is staunchly Republican while the other two are more mixed theologically.
