Therefore put on the full armor of God, so that when the day of evil comes, you may be able to stand your ground, and after you have done everything, to stand
What do you do when the evil day comes? You put on the whole armour of God. The Greek word for “put on” comes from the military vocabulary of the first century. It was used for the last thing the soldier would do before going out to battle.
When the call came, the soldier would grab his armour, put it on, and head for the fight. Our text is telling us that when the evil day comes before you go to battle, make sure you’re in uniform. This can be expressed in Ecclesiastes 10: 11, “If the snake bites before it is charmed, then there is no advantage for the charmer.”
In other words, this scripture means, do not wait for the evil day before you take actions against it. You can conquer the evil day even before it materializes. Hallelujah! We must not allow the assailants of the wicked one take us out of the Will of God.