The devil is not a winner ... he's a loser! He's only a winner to the extent that we let him win and we don't have to do that. Satan gets the upper hand over Christians because they don't know any better ... they don't have the proper tools and they don't know how to use them.
We don't realize that it isn't us causing bad things to happen ... that the devil is the cause. These are spiritual things coming from fear or shame ... and we take the blame for their happenings. When we get attacked by the devil, we really don't understand who's doing it and why. The "why" is because the devil does not want us getting intimate with our Heavenly Father, and he does everything he knows how to do to keep us away from that intimacy.
We cannot "think" the devil away. We must speak the Word to chase him away. When we speak God's Word out, the thought that was there disappears. This is when the victory comes ... when we know what to say and when to say it.
God's Word, when spoken aloud, is what brings us the victory in dealing particularly with the thoughts that Satan is trying to bombard us with to cause us any kind of difficulty or misery.
Reverend Robert W. & Mary C. Butler