Concerning Exodus 32, if God can plan in advance to pronounce a sentence and then recant it (as your article implies), then could He not put a person's name into the book of life (knowing that such a man will not endure to the end), and then later remove it if He so chooses?

But, Josh that IS NOT what the Scripture states:

Revelation 13:8 All who dwell on the earth will worship him, whose names have not been written in the Book of Life of the Lamb slain from the foundation of the world. and [color:#000099] Revelation 17:8 The beast that you saw was, and is not, and will ascend out of the bottomless pit and go to perdition. And those who dwell on the earth will marvel, whose names are not written in the Book of Life from the foundation of the world, when they see the beast that was, and is not, and yet is.

That was quite a long article on Hebrews 6, but two things about it go against your case. For one, his argument is based on the idea that the people spoken of passed up the opportunity to be saved...."...who may even have made some profession of faith in Him, yet turn around and walk away from full acceptance, are given the severest possible warning. Persistent rejection of Christ may result in such persons’ passing the point of no return spiritually, of losing forever the opportunity of salvation."

Then I submit that you do not understand Reformed Doctrine. Man does have a will, it is not just a free as the Arminian thinks it is. Man makes decisions! They make decisions based on the knowledge they possess. Thus they can turn down a genuine offer. They reason they turn it down though is because they have not been changed by the Holy Spirit to see it (John 3:1-8). This man until he is changed by the Holy Spirit will not seek after God (Rom 3). He can not seek after God because he is dead in trespasses and sin (Eph 2). Thus as John 1:5 says 5 And the light shineth in darkness; and the darkness comprehended it not.

Additionally, the author's whole argument:

"People can go to church for years and hear the gospel over and over again, even be faithful church members, and never really make a commitment to Jesus Christ. That kind of person is addressed here."....Is clearly contradicted by vs 9, which says,
"But beloved, we are persuaded better things of you, and things that accompany salvation (literally: 'that you are holding fast salvation'), though we thus speak."

The word "But" refers to a different audience!

This term shows a change of audience and a move towards a change from a message of warning to a message of encouragement. That the address is to believers is further confirmed by the expression of confidence that “better things” [not the same things] could be said of them (as compared to those who were being warned in the preceding verses).

The “things that accompany salvation” are their works which verify their salvation (Eph. 2:10; James 2:18,26). The very statement implies that the things described in 5:11–6:5 do not accompany salvation but are indicative of unbelief and apostasy. though we speak in this manner. Though it had been necessary to speak about judgment in the preceding verses, the writer assures the “beloved,” those who are believers, that he is confident of their salvation.

Reformed and Always Reforming,