Matthew 22:29

But Jesus replied to them, “You are all wrong because you know neither the Scriptures (which teach the resurrection) nor the power of God (for He is able to raise the dead).

Our defeat will come because of the lack of knowledge of the word of God. There is power available to us through the word for all our circumstances that the devil cannot defeat. Our reinforcement comes from knowledge of the word and study of the bible. When we speak the word, we defeat the enemy and glorify the power of God.