But let us, since we belong to the day, be sober, putting on the breastplate of faith and love, and, for a helmet, the hope of salvation.
putting on: The grammar of this verse points to "a decisive, once-for-all step" (Morris 99). The idea is that one should put his armor on and keep it on. The armor is donned at the time one becomes a Christian. The armor is more fully described in Ephesians 6, but here the apostle is concerned only with the "breastplate" and the "helmet" used to defend the two most vital parts of the anatomy, the heart and the head. "The head needs to be kept from error, the heart from sin" (Jamieson, Fausset, and Brown 391).