Speaking the truth

Why is it so important to speak the truth? or, why is it a sin to lie? I was thinking about this the other day while reading Isaiah 59. There's a picture painted of a people of deceit, who live and speak and believe lies, resulting in destruction, murder and all sorts of injustice. Then I thought about the power of words. Someone once said that words have greater power than we realize, but I've come to believe that it's not the words that are spoken that have power but it's who speaks them that gives them any validity and weight. Think of it this way, we know that what God says is true, why? because everything God has ever said has proven to be true, so we trust that He will keep His word. In the past, when a person gave their word it was an oath, a promise they were tied to. If they turned out to be a scoundrel their word was worth nothing more than a meaningless utterance. In our postmodern, morally wanting society people throw words around without any thought to their significance. How do we become people of integrity if we do not keep our word? How can we have any impact on this world when we show ourselves to be untrustworthy. And it's not just speaking the truth, but speaking it from the heart and to the heart like Ps 15:1,2 says, "LORD, who may dwell in your sanctuary? Who may live on your holy hill? He whose walk is blameless and who does what is righteous, who speaks the truth from his heart." Truth spoken from the heart is truth received by the heart. We're attacked by lies everyday, they're like flaming arrows aimed at our hearts (Eph 6:16). Unfortunately we often believe them, but if we speak the truth in our hearts we are changed, we are set free from the lies that bind us. (John 8:32) So speaking the truth makes us like Christ, our words begin to have a greater weight, and our hearts are free as we trust in God and the truth of His word. So lying is a sin because it is the opposite of who God is and because it binds us and destroys our hearts. Satan is called the "Father of Lies"(John 8:44), because he is devoted to binding and destroying people (John 10:10), where as God is devoted to liberating and giving life (Is 61:1-4)!