And presently the fig tree withered away. And all things, whatsoever ye shall ask in prayer, believing, ye shall receive. We are taught in Christianity to go out and spread the Word to all peoples of the land. We spread the Word by speaking it to others. We know that faith comes by hearing the Word of God.
Words spoken can help, hurt, instruct, comfort, convey learning and so on.
The spoken word is a powerful instrument that can be used for good or evil. We go out of our way as Christians to avoid evil talk. We do not even want to hear evil around us. We avoid evil because we know that Satan conveys all things that are evil in this world. Satan waits for us to falter so that he may act on our weak moment in faith to our Father.