D. James Kennedy - PCA, not mainline (PCUSA is mainline)
C.S.Lewis - different era and no fan of Anglican liberalism.
Schaeffer - what mainline denomination did he actively champion? Also, a different era.
As a member of an SBC church, I’d say Santorum is right. Of course, the RCs were wrecked theologically as a consequence of Vatican II. The SBC is trending in the same wrong direction as the mainline denominations.
Protestants are Protestants.
Catholics are Catholics.
In either case, their churches tend to be split, as I stated in the article. I’m sure there are “liberals” and “conservatives” in each, who prefer to think of their beliefs as “mainline.”
However, I hope none are bigoted or haughty enough to dictate which handfuls of tares, and the wheat along with it, may be uprooted, and called “gone from the world of Christianity.”
Pleasant pondering with the Lord. I suggest the entire article. Then again, I wrote it. ;-> Also, the comments beneath it.