Although there is alot of Hollywood spin in this film, I highly recommend those that want to understand spiritual warfare to watch this movie.
I'm sure they didn't mean to, but this movie accurately portrays how the spirit realm invades your mind and plants thoughts there.
they have a plan, an ultimate agenda and goal to accomplish, they study you so they know how to attack "Every day they wrest my words: all their thoughts [are] against me for evil. They gather themselves together, they hide themselves, they mark my steps, when they wait for my soul." Psalms 56:5-6
"In the dark they dig through houses, [which] they had marked for themselves in the daytime: they know not the light." Job 24:16
they form a team to accomplish their agenda: "When the unclean spirit is gone out of a man, he walketh through dry places, seeking rest; and finding none, he saith, I will return unto my house whence I came out. And when he cometh, he findeth [it] swept and garnished.Then goeth he, and taketh [to him] seven other spirits more wicked than himself; and they enter in, and dwell there: and the last [state] of that man is worse than the first." Luke 11:24-26
they attack you while you sleep, and put thoughts in your mind: "Now a thing was secretly brought to me, and mine ear received a little thereof. In thoughts from the visions of the night, when deep sleep falleth on men, Fear came upon me, and trembling, which made all my bones to shake. Then a spirit passed before my face; the hair of my flesh stood up: It stood still, but I could not discern the form thereof: an image [was] before mine eyes, [there was] silence, and I heard a voice, [saying], ..." Job 4:12-16
they work within wicked men: "Hide me from the secret counsel of the wicked; from the insurrection of the workers of iniquity: Who whet their tongue like a sword, [and] bend [their bows to shoot] their arrows, [even] bitter words: That they may shoot in secret at the perfect: suddenly do they shoot at him, and fear not. They encourage themselves [in] an evil matter: they commune of laying snares privily; they say, Who shall see them? They search out iniquities; they accomplish a diligent search: both the inward [thought] of every one [of them], and the heart, [is] deep." Psalms 64:2-6
We have the authority of Jesus Christ to fight these thoughts: "(For the weapons of our warfare [are] not carnal, but mighty through God to the pulling down of strong holds;) Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ;" 2 Cor 10:4-5
Russ Dizdar has a good teaching on inception as well: