The Armour of Satan

No man is born on God's side. He is by default on the enemy's side.

In his natural state, we could think of his characteristics as a suit of armour—one he made himself. He has a breastplate, not of righteousness, but of self-righteousness. He has the shield of unbelief and the sword of the flesh.

It's only when he encounters Christ, the Captain of the Lord's Hosts, that he surrenders, removes his own armour, and takes up the Whole Armour of God then presented to him.

We see that it is through prayer he is to put each piece on. In being so kitted out, he is able to better resist his former captain, Satan, and all his forces. In addition, it is through this prayer that his behaviour conforms more and more to the perfect righteousness of Christ which is his by the gift of God's free grace.