The end the book of Ephesians sounds like a general's peptalk he might give to an army before they head off to battle. In essence, that's what it is. Paul chooses his words carefully - and very specifically gives Jesus-followers instructions on how to fight a spiritual battle against Satan.
"This is for keeps, a life-or-death fight to the finish against the Devil and all his angels." Personally, I know the Devil is real just like I know Jesus is real - you can't see him, but you can see very real effects of his presence. Satan tricks people. He lies. Sure, sin is fun (I know, because I'm a sinner myself), but only fun for a short while. Eventually, sin is exposed - you can't hide it. Then it ruins you, and you're even worse than you started. Satan lies.
So Paul tells us to be prepared. With what weapons? We must learn how to apply truth, righteousness, peace, faith, and salvation in order to be warriors for the Kingdom. Prayer is essential. Knowing God's word is also very important. Paul calls it an "indispensable weapon." If that's the case, I need to read more.
A Prayer: God, help me take this battle seriously. I didn't tell a single person about Jesus today - not ONE! I'm ashamed about that, and Satan is thrilled. Help me to realize the urgency of your Message. Instill your Message in my heart so that I know it inside and out. Prepare me for battle.