Just a random note from my recent reading of Hebrews.
It annoys me no end how TRs try to bracket off the Biblical testimony to the reality of apostasy into a few "problem passages" that can then be explained away. Hebrews 6:4-6 is a great example of this problem. The problem of course is not merely that the passage cannot be successfully explained away without resorting to ridiculous exegesis. More important is that the passage cannot be isolated in the first place. On the contrary, by my count, 71 of the 303 verses in Hebrews are warnings against apostasy, and the author apparently does not consider himself to be dealing with a mere hypothetical. In other words, 1/4 of the letter is devoted quite explicitly to the issue, with much of the rest providing supporting argument. Indeed, in the first six chapters, 41 of 101 verses deal with the issue. Essentially, apostasy is the theme of the first half of Hebrews, and 6:4-6 is simply the most irrefutably explicit discussion of it.
*sigh* Yes, I still have a chip on my shoulder from my GPTS days.