I don't think anyone would disagree that there is power in words. Whether you're on the receiving end of a scathing accusation or you're encouraged by a timely complement, words have the ability to impact you in a lasting way.
James puts it this way in chapter 3 verse 9 of his letter: "With the tongue we praise our Lord and Father, and with it we curse human beings, who have been made in God’s likeness."
If only we used the tongue for the gift that it really is: to praise our Lord and Father. Your words don't just articulate your heart's desire - they affirm it. Our God is Creator, He created the heavens and the earth by what he said.
In some ways your words act as a filter. The heart is deceitful - you can become hard and judgemental towards someone, but you don't necessarily have to tell them. Instead, you can use words that are full of grace and truth. And, you have the ability to speak the most powerful word: Jesus.
There is no other name by which me must be saved. Why is that only Jesus' name is spoken in vein? That's not a coincidence. Speak to build up, not to blow up - speak 'Jesus.'