"There are warnings against apostasy which would seem to be quite uncalled for, if the believer could not fall away, Matt. 24:12; Col. 1:23; Heb. 2:1; 3:14; 6:11; I John 2:6. But these warnings regard the whole matter from the side of man and are seriously meant. They prompt self-examination, and are instrumental in keeping believers in the way of perseverance. They do not prove that any of those addressed will apostasize, but simply that the use of means is necessary to prevent them from committing this sin. Compare Acts 27:22-25 with verse 31 for an illustration of this principle." -- Berkhof, Systematic Theology, p. 548.
"This passage [Heb. 6:4-6] has been interpreted in four ways: (1) that the danger of a Christian losing his salvation is described, a view rejected because of Biblical assurances that salvation is a work of God which cannot be reversed; (2) that the warning is against mere profession of faith short of salvation, or tasting but not really partaking of salvation (The New Scofield Reference Bible, p. 1315); (3) that hypothetically if a Christian could lose his salvation, there is no provision for repentance (The Ryrie Study Bible, p. 1736); (4) that a warning is given of the danger of a Christian moving from a position of true faith and life to the extent of becoming disqualified for further service (1 Cor. 9:27) and for inheriting millennial glory. The latter is the interpretation adopted here." -- Zane C. Hodges in The Bible Knowledge Commentary: New Testament Edition, p. 794.
NOTE: Prof. Hodges' view of the warning passages in Hebrews was not shared by all members of the faculty of Dallas Theological Seminary when I was a student there 1976-1981. In fact, I'm not sure it was even shared by a majority of them. Rumor has it that he was asked to write the commentary on Hebrews because his view was considered unique and not widely in print. - CAS
The following is from Charles Hodge's commentary on I Corinthians, specifically 8:11, "And through thy knowledge shall the weak brother perish, for whom Christ died?" This excerpt shows not only his support for eternal security, but also his support for election and limited atonement - CAS
"That is, shall your knowledge be the occasion of the perdition of a weak brother? There are three forms in which the apostle expresses the consequence of doing what the conscience is not satisfied is right. In v. 7 he says, the conscience is defiled; here, he says the man perishes or is lost; in Rom. 14, 23, he says, "He that doubteth is damned (comdemned) if he eat." All these forms of expression amount to the same thing. Guilt, condemnation and perdition are connected. The one implies the other. Whatever brings guilt on the conscience exposes to condemnation, and condemnation is perdition.
"For whom Christ died. There is great power and pathos in these words. Shall we, for the sake of eating one kind of meat rather than another, endanger the salvation of those for whom the eternal Son of God laid down his life? The infinite distance between Christ and us, and the almost infinite distance between his sufferings and the trifling self-denial required at our hands, give to the apostle's appeal a force the Christan heart cannot resist. The language of Paul in this verse seems to assume that those may perish for whom Christ died. It belongs, therfore, to the same category as those numerous passages which make the same assumption with regard to the elect. If the latter are consistent with the certainty of the salvation of all the elect, then this passage is consistent with the certainty of the salvation of those for whom Christ specifically died. It was ablolutely certain that none of Paul's companions in shipwreck was on that occasion to lose his life, because the salvation of the whole company had been predicted and promised; and yet the apostle said that if the sailors were allowed to take away the boats, those left on board could not be saved. This appeal secured the accomplishment of the promise. So God's telling the elect that if they apostatize they shall perish, prevents their apostasy. And in like manner, the Bible teaching that those for whom Christ died shall perish if they violate their conscience, prevents their transgressing, or brings them to repentance. God's purposes embrace the means as well as the end. If the means fail, the end will fail. He secures the end by securing the means. It is just as certian that those for whom Christ died shall be saved, as that the elect shall be saved. Yet in both cases the event is spoken of as conditional. There is not only a possibility, but an absolute certainty of their perishing if they fall away. But this is precisely what God has promised to prevent. This passage, therefore, is perfectly consistent with those numerous passages which teach that Christ's death secures the salvation of all those who were given to him in the covenant of redemption. There is, however, a sense in which it is scriptural to say that Christ died for all men. This is very different from saying that he died equally for all men, or that his death had no other reference to those who are saved than it had for those who are lost. To die for one is to die for his benefit. As Christ's death has benefited the whole world, prolonged the probation of men, secured for them innumerable blessings, provided a righteousness sufficient and suitable for all, it may be said that he died for all. And in reference to this obvious truth the language of the apostle, should any prefer this interpretation, may be understood, 'Why should we destroy one for whose benefit Christ laid down his life?' All this is perfectly consistent with the great scriptural truth that Christ came into the world to save his people, that his death renders certain the salvation of all those whom the Father hath given him, and therefore that he died not only for them but in their place, and on the condition that they should never die."