17. Ye, therefore, beloved. After having shewn to the faithful the dangers of which they were to beware, he now concludes by admonishing them to be wise. But he shews that there was need of being watchful, lest they should be overwhelmed. And, doubtless, the craft of our enemy, the many and various treacheries which he employs against us, the cavils of ungodly men, leave no place for security. Hence, vigilance must be exercised, lest the devices of Satan and of the wicked should succeed in circumventing us. It, however seems that we stand on slippery ground, and the certainty of our salvation is suspended, as it were, on a thread, since he declares to the faithful, that they ought to take heed lest they should fall from their own steadfastness.
What, then, will become of us, if we are exposed to the danger of falling? To this I answer, that this exhortation, and those like it, are by no means intended to shake the firmness of that faith which recumbs on God, but to correct the sloth of our flesh. If any one wishes to see more on this subject, let him read what has been said on the tenth chapter of the First Epistle to the Corinthians.
The meaning is this, that as long as we are in the flesh, our tardiness must be roused, and that this is fitly done by having our weakness, and the variety of dangers which surround us, placed before our eyes; but that the confidence which rests on God's promises ought not to be thereby shaken.