Continuing on with my notes from How To Say No to a Stubborn Habit by Erwin Lutzer:
Chapter 11, Resisting Satanic Activity
Though "the flesh" gives us plenty of trouble, Satan is also at work "undercover" in our everyday lives and struggles with sin (i.e., he tempted Ananias and Sapphira to lie (Acts 5:3), can tempt people sexually (I Cor. 7:5) or in their standing up for Christ (Luke 22:31), can hinder people from doing God's will (I Thes. 2:18), blinds people's minds (II Cor. 4:4), "snatches" the Word from people's minds lest they be saved (Luke 8:12). He is not at work just when something bizarre or eerie is happening.
Satan's sphere of influence is the heart or mind, the inner, spiritual being (he put it in Judas' heart to deny Christ [John 13:2], tempted Ananias to lie, mentioned earlier). He is our " adversary ... a roaring lion, walketh about, seeking whom he may devour" (I Peter 5:8).
Yet, though he may tempt us, we're still responsible for our choices: Ananias and Sapphira died. "He may suggest any sin imaginable, but ultimately you make the choice. He cannot work independently of your cooperation."
We may be tempted to think that if we leave Satan alone, he'll leave us alone, but Lutzer tells such people, "You've just made peace with the enemy by refusing to do battle with him."
One of his most effective weapons is fear of what will happen if we do one thing or don't do another, but we have to remember he is a liar and that father of lies (John 8:44).
But we have the authority to resist and renounce his activity. The first thing to do is to check our spiritual armor (Eph 6:10-18) and see if anything is missing or not up to par. Lutzer then comments just on the "breastplate of righteousness." Any sin gives him a foothold, but that disappears once the sin is confessed and forsaken. Personal righteousness is a shield from demonic attack. "Satan's arrows are deflected when up against a conscience void of offense." If we're being troubled in any area, we need to check whether we've given Satan any ground or have some sin we've not taken care of by confessing or forsaking it. And so, too, with the other pieces of armor.
"Satan has no rights, but he won't admit it." "Christ's death and ascension to heaven won a legal victory over all satanic forces" (Col. 2:15, Eph. 1:20-23)) and therefore we can resist him (James 4:7, Eph. 4:26-27). Lutzer then reasons that "(1) Christ's ascension to heaven placed him above all rule, authority, power, and every name that is named, and (2), all things are under His feet -- no power exists in the universe without Christ's permission. [(3) we're] seated with Christ in heavenly places" according to Ephesians 2, so we have authority over Satan though we may feel weak and helpless.
We can confront wicked powers then by following the example of Christ in Matthew 4: tell them to be gone based on the promises of Scripture. "The power of the Word of God is unleashed when you bring yourself under its authority." The disciples could not cast out a demon due to unbelief (Luke 9:47-48).
I John 4:4: "Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world."
(Disclaimer: My purpose in jotting down these notes is not to post "the answer" so that people don't have to buy the book: on the contrary, I hope anyone struggling with persistent sin will buy the book. There is so much more there that is so rich. Rather, this is just an exercise for me to review what I have read and studied.)