Paul uses the example of soldiers because of the time and place they were in. They may have been familiar with soldiers being in Ephesus. More importantly, soldiers do not fight wars alone by themselves. They stand together against the attacks of the enemy. Likewise we need to stand together as the body of Christ. This is more visible when Paul says, “we do not” rather than “you do not”.
“Flesh and blood” here refers to people. We fight against the spirit behind the flesh and blood that we see. But through flesh and blood is still how those powers manifest themselves. This is why we need to remember not to always be upset with people, but pray for the spirit working in them that causes such hostile behaviors.
As we better understand who we are fighting in this spiritual war, we learn to pray more for people, to appreciate people, and to see them through the eyes of our Heavenly Father, for He loves them too. – Eruore Oboh