There is an old testament battle, the account of which contains a detail I enjoy because it is one of clever espionage.
In Judges 9 we have the story of a sibling quarrel between the Ephramites and the Gileadites that became so heated they went to battle against each other.
The Gileadites won and gained control of the fords of the Jordon River that escaped Ephramites needed to cross to return safely home.
When an Ephramite would approach the ford the Gileadites would stop him and ask .. "Are you an Ephramite?" and if the one desiring to cross would say 'No, I am not!' then the Gileadites would demand.. "Say, Shibboleth!" and if the man said .. "Sibboleth!" he was known to indeed be a Ephramite because the Ephramites could not pronounce the 'sh'!
Caught in his lie, he was revealed as the enemy.
I heard a modern version of that story yesterday morning. During WW II the Americans had a similar way of discerning who was a spy among their soldiers. A suspected spy would be called into the commander's office and told ... "Sing the second verse of the Star Spangled Banner!" If the soldier clicked his heels in a smart salute and a quick 'Yes, Sir' followed by a correct rendition of the second stanza of the national anthem, he was immediately arrested as a spy ! Why? No American knows the second stanza!
We have another example in I John 4:2b,3
"Every spirit that confesses that Jesus Christ has come in the flesh is of God, and every spirit that does not confess that Jesus Christ has come in the flesh is not of God. "
Here we are told how we can know on whose side someone is .. friend or foe!
Someone who is of God, will confess who Jesus is ! They will declare Jesus to be God. They will know His character and will 'confess' it in their own life -- their words, their actions will reflect the image of the One they believe in. If they cannot, we know that they are not of God but of the enemy!
"He that says (confesses) he abides in Him ought himself also to walk just as He walked."
I John 2:6
We too, have an enemy who often stands at the crossings of our life. He stands in the way of those who pass by demanding of them ... "Can you say Jesus, confessing Him to be the Lord of your life?"
The answer a person gives will either cause Satan to sneer with glee or hang his head and flee!
"Therefore submit to God. Resist the devil and he will flee from you !"