Gird up the loins of your mind. — A metaphor from persons gathering up the flowing Oriental dress (which had been let down for repose), so as to be ready for energetic action (e.g., 1 Kings 18:46, for running; Job 38:3, for arguing). What exact kind of action St. Peter meant them here to prepare for we need not inquire. A “mind,” rather than “soul” or “heart,” seems to bespeak practical intelligence. Thus when the Galatians, too, began to fall from evangelical to Judaic religion St. Paul calls them “senseless” (Galatians 3:1).
Be sober. — Not in the literal sense, but with the same notion of alertness as in “gird up”; sobriety and wakefulness are often combined (e.g., 1 Peter 5:8; 1 Thessalonians 5:6).
Hope to the end. — Literally, hope perfectly, or, thoroughly, or, with completeness. “Indeed this hope,” says Leighton, “is perfect in continuance, it is a hope unto the end, because it is perfect in its nature.” The chief thought, however, is that the hope should not be half-hearted, dispirited. St. Peter brings us back to what he began with, that ours is a living hope. The exhortation is exactly of the same nature as that which pervades the Epistle to the Hebrews (see, for instance, Hebrews 3:6; Hebrews 3:14; Hebrews 6:11), and for the same reason — i.e., that spiritual sloth, combined with fear of man, was beginning to turn these Jewish Christians back to dead works. “Hope on,” in these passages, is tantamount to “remain Christians.”
For the grace. — Not exactly” hope for the grace,” i.e., expect confidently that it will come: rather, “hope upon the grace,” as in 1 Timothy 5:5, the only other place where the same construction is used, and where it is rendered “trusteth in God.” Here, therefore, it is, “confidently hope (for salvation, glory, &c.) on the strength of the grace.” The grace is the same as in 1 Peter 1:10.
That is to be brought. — “If we will render it strictly, it is, That is a-bringing to you. That blessedness, that consummation of grace, the saints are hastening forward to, walking on in their way, wheresoever it lies indifferently, through honour and dishonour, through evil report and good report. And as they are hastening to it, it is hastening to them in the course of time; every day brings it nearer to them than before; and notwithstanding all difficulties and dangers in the way, they that have their eye and their hopes upon it shall arrive at it, and it shall be brought safe to their hand; all the malice of men and devils shall not be able to cut them short of this grace that is a-bringing to them against the revelation of Jesus Christ” (Leighton). On the tense, see also Note on 1 Thessalonians 1:10. Notice also that it is now the personal Name, not the official title. St. Peter is enforcing the gospel as we know it; we no longer “search unto whom” the title of the Messiah belongs.