Ephesians 6:13

διὰ τοῦτο – because of this. Paul refers back to what he said previously in 6:12, he reminds us that the reason we must take up the whole armor of God is because we do not wrestle against flesh and blood. Our battle is a spiritual battle, therefore our armor and weapons must be spiritual.

ἀναλάβετε τὴν πανοπλίαν τοῦ θεοῦ – take up the whole armor of God. The word πανοπλία refers to the complete set of tools used in battle. We are to make use of everything that God has given us in this battle and not leave any to the side. The genitive case demonstrates that these are not just any set of tools, but they are God’s tools. That is to say, it is the very same set of tools that God uses to defeat the very same enemy.

ἵνα δυνηθῆτε ἀντιστῆναι ἐν τῇ ἡμέρᾳ τῇ πονηρᾷ – in order that you might stand against in the day of evil. The subjunctive clause here reveals the purpose of taking up the whole set of tools God has given us. The common translation “withstand” masks the fact that the word ἀντιτάσσομαι is an offensive word. Rather than simply bearing up under the attacks of the enemy, we are to actively oppose him. The use of the aorist shows us that although the battle is ongoing, the fact of our withstanding is a conceptually complete concept. Because these are God’s implements of war, if we take them up, we cannot fail to withstand. This is true even in the day of evil.

καὶ ἅπαντα κατεργασάμενοι στῆναι – And having done all, to stand. Paul makes explicit in the last clause what was implicit in the grammar of the former. In the day of evil, having accomplished the task of taking up all of God’s implements of war, we will be victorious. Although the idea of an ongoing battle is not missing from this concept, the phrasing in this passage is definite and refers to a single day. There is a decisive day where the battle is won or lost, and because we take up the whole armor of God, we know it will be won.