As Christians we don't often realize the power of the words that we speak out of our mouths. Our words have the power to create things in the atmosphere around us. They can create life or they can create death. The scripture says in Proverbs 18:21 " Death and life are in the power of the tongue, and those who love it will eat its fruit." We must choose each day to use our tongues to bring life and not death, to bless and not curse.
We see an example of this in the story of David and Goliath. Goliath was dead long before David's stone hit him because of what David was speaking. Those words were going into the atmosphere and creating the circumstances which resulted in Goliath's defeat.

1 Samuel 17:46-51 "Then David said to the Philistine, “You come to me with a sword, with a spear, and with a javelin. But I come to you in the name of the Lord of hosts, the God of the armies of Israel, whom you have defied. This day the Lord will deliver you into my hand, and I will strike you and take your head from you. And this day I will give the carcasses of the camp of the Philistines to the birds of the air and the wild beasts of the earth, that all the earth may know that there is a God in Israel. Then all this assembly shall know that the Lord does not save with sword and spear; for the battle is the Lord’s, and He will give you into our hands.”

So it was, when the Philistine arose and came and drew near to meet David, that David hurried and ran toward the army to meet the Philistine. Then David put his hand in his bag and took out a stone; and he slung it and struck the Philistine in his forehead, so that the stone sank into his forehead, and he fell on his face to the earth. So David prevailed over the Philistine with a sling and a stone, and struck the Philistine and killed him. But there was no sword in the hand of David. Therefore David ran and stood over the Philistine, took his sword and drew it out of its sheath and killed him, and cut off his head with it. And when the Philistines saw that their champion was dead, they fled."

In James 3:9-10 he warns us about the power of our tongues and how we are to use it. He says, "With it we bless our God and Father, and with it we curse men, who have been made in the similitude of God. Out of the same mouth proceed blessing and cursing. My brethren, these things ought not to be so." There is an old saying "Open mouth insert foot"! We all have had times I'm sure in which we end up saying things without thinking in which we regret saying. Words are powerful when they are hurtful to those around us that hear them. So then, my beloved brethren, let every man be swift to hear, slow to speak, slow to wrath; for the wrath of man does not produce the righteousness of God. James 1:18-20.