“For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.”
(Eph. 6:12)
The Christian’s real foe is not physical but spiritual. The spiritual can and does use the physical; but at the root it is always to be found in the spiritual, as in the case of Peter (Matt. 16:230.) Therefore, because of this fact, Paul tells us our weapons in this ongoing warfare are to be spiritual, not carnal or flesh (2 Cor, 10:4). You cannot fight spiritual battles with carnal means; it’s a no-winner! Jesus overcame Satan by the use of spiritual means (Matt. 4:1-11). Notice also what John says in 1 Jn. 2:14b.
Generally speaking, Israel's physical foes in the Old Testament become our spiritual foes in the New. For example, the book of Joshua applied this way brings great enlightenment and encouragement to a child of God in his or her daily spiritual battles. This is why it is so important, I believe, to be familiar with the the Old. The writers of the New Testament used the Old Testament in this way. The book of Hebrews is a good example. We need, what I like to term it, an encyclopedic knowledge of the Word.
“God’s two-edged sword slices both ways; both to wound and to heal”
(rds)