John Calvin Commentary Ephesians 6:13

"Wherefore take up the whole armor of God, that ye may be able to withstand in the evil day, and, having done all, to stand." — Ephesians 6:13 (ASV)

Wherefore take unto you. Though our enemy is so powerful, Paul does not infer that we must throw away our spears, but that we must prepare our minds for the battle.

A promise of victory is, indeed, involved in the exhortation, that ye may be able. If we only put on the whole armor of God, and fight valiantly to the end, we shall certainly stand. On any other supposition, we would be discouraged by the number and variety of the contests; and therefore he adds, in the evil day.

By this expression he rouses them from security, bids them prepare themselves for hard, painful, and dangerous conflicts, and, at the same time, animates them with the hope of victory, for amid the greatest dangers they will be safe.

And having done all. They are thus directed to cherish confidence through the whole course of life. There will be no danger that cannot be successfully met by the power of God; nor will any who, with this assistance, fight against Satan, fail in the day of battle.