I was reading a spiritual war book, and this is one of the most important quotes when it comes to spiritual warfare ...

Ephesians 6: 14-17

14 Stand, then, with your loins girt about with truth, and clothed with the breastplate of righteousness, 15 and your feet shod with the preparation of the gospel of peace. 16 Above all, take the shield of faith, with that you may quench all the fiery darts of the evil one.17 And take the helmet of salvation, and the sword of the Spirit, which is the word of God;

In this way we are protected against the darts of the enemy, as you exemplify here, he tries to manage the mind, placing thoughts contrary to God and seeks contention and division, among other things.