Proverbs 18:21

Death and life are in the power of the tongue, and those who love it and indulge it will eat its fruit and bear the consequences of their words.  

We have authority on this earth through our words in our lives.  That’s the reason the devil wants to stir us up, so we speak words that are not faith.  The devil can’t act unless we talk about doubt, fear, defeat.  Now, God in the bible gives us words of power and authority to produce in our lives.