This question rages on the major message boards. The initial answer seems to be “no.” For those of us in former Baptist circles, who fought old-school liberalism to the death, and have the scars to prove it (no joke; I was actually physically attacked in college on this point), it would seem that the PCA isn’t going liberal. The denomination believes in inerrancy (sort of) and the Westminster Confession (loosely speaking). The objection seems to be: if we say the PCA is going liberal, that waters down the term. The PCUSA is liberal and there is a big difference.”
But the road to liberalism takes different turns. This morning i just finished rereading Gary North’s Westminster’s Confession: The Abandonment of the Van Til Legacy. Other issues about theonomy aside, North made several observations which seem to have been vindicated: With the hiring of Ed Clowney as President, Westminster Seminary moved towards a broader evangelical base. They never rejected the old Confessionalism, but with the move towards neo-Evangelicalism it became harder to maintain the old Confessionalism.
I actually think Westminster Philly moved back towards a more confessional stance in the last ten years. However, what North projected of WTS actually is true of the PCA. If by liberal one means “denying the supernatural,” then the PCA isn’t going liberal, at least not anytime soon. I think it is better to say they are going “neo-evangelical,” best represented by Christianity Today. Is neo-Evangelicalism liberal? Not at first glance. However, most neo-evangelical movements eventually go liberal. Christianity Today, a bastion of supposedly right-wing Christianity, at one time hosted a symposium and invited (if not endorsed) pro-abortion physicians and theologians (one of the theologians, by the way, who endorsed abortion, also wrote an essay in Theonomy: A Reformed Critique; just thought I would throw that out there.)
Here is the difference between liberals and mainstream status quo institutional conservatives: liberals are cunning and they know they are consistent in terms of their covenant-breaking (whereas conservatives think liberals will adopt a common-ground neutral playing field, Roe v. Wade notwithstanding). They know just how to play the game to marginalize conservative. And in terms of the PCA, they probably don’t even see themselves as “liberal.” I don’t even think they are liberal. However, history does play out that when Confessional bodies seek the lowest-common denominator, they usually get it. At which point the question comes up: how exactly are you Confessional?