Being a Marine brat, I love Joe Rosenthal’s picture of the Marines taking Iwo Jima in WWII. It tells of our victory, removing the defeated Japanese flag and replacing it with ours.
In most cultures, a flag is used to identify your country, to mark victory (as above) and often used as a place to “rally around”. I love the way the kids in our area have a “See You at the Pole” day where they gather at the flag pole of their school to pray.
In scripture, one of the names of God is Jehovah Nissi (Exodus 17:15) meaning the Lord our Banner. We are identified with Him and rally around Him, especially at church. Jesus is our victorious Captain (Hebrews 2:10). He has displaced the enemy in our lives and set up His kingdom of love. There we are protected, loved and accepted in the beloved. Not so different from WWII but oh, so much better!