"Finally, be strong in the Lord, and in the strength of His might.
11. Put on the full armor of God, that you may be able to stand firm against the schemes of the devil.
12. For our struggle is not against flesh and blood, but against the rulers, against the powers, against the world forces of this darkness, against the spiritual forces of wickedness in the heavenly places.
13. Therefore, take up the full armor of God, that you may be able to resist in the evil day, and having done everything, to stand firm.
14. Stand firm therefore,
(1) having girded your loins with truth,
(2) and having put on the breastplate of righteousness, . . .
15. (3) and having shod your feet with the preparation of the gospel of peace;
16. in addition to all,
(4) taking up the shield of faith with which you will be able to extinguish all the flaming missiles of the evil one.
17. (5) And take the helmet of salvation,
(6) and the sword of the Spirit, which is the word of God."
"Schemes" is the translation of the original Greek meth-od-i'-ah (TDNT 5:102,666), which may also be rendered cunning, deceit, craft, or trickery. Compare in the KJV the use of methodiah in Ephesians 4:14, where it is translated “lie in wait” and also adds, “to deceive”.
Ultimately our spiritual warfare is waged against invisible forces of darkness who are behind the immediate and apparent causes of our battles. Yes, people can be unwittingly influenced and deceived by these forces of evil.
These powers are demons of lesser rank who want to possess human beings (McGee, 5:279).
We are to “ . . . take up the full armor of God, ...” so that we are "able to resist” the Lord's enemies.
cf. 1 Thessalonians 5:8; cp. Titus 3:1-8).