What is mercy? And why is it important? Mercy is "compassionate or kindly forbearance shown toward an offender, an enemy, or other person in one's power" (http://dictionary.reference.com/browse/mercy). It is the refusal to give an offender the punishment that he or she deserves.
What makes mercy important? Before we answer this question, we must all remember that none of us deserve mercy. Mercy can also not be earned. When we rebelled against God, God showed mercy on us. He could have allowed our lives to be taken from us the moment that we rebelled, but He did not make this choice. Rather, He chose to let us continue to live. In this way, God has even shown some mercy to those who have refused to accept Him. He chooses to let them continue to breathe, and to live their short life on this planet. He did not have to allow this.
God has shown mercy to those who have accepted Jesus, as well. In fact, He has shown us so much mercy that I do not believe that it could be adequately expressed in words. Through the sacrifice of Jesus Christ, God has shown us such mercy and grace that we cannot adequately describe it. Because of the sacrifice of Jesus Christ, we can now live a life in eternity.
During His ministry on earth, Christ also showed mercy to those that He encountered. Remember the official at Cana of Galilee who had an ill son (John 4:46-54)? What about the leper after the sermon on the mount (Matthew 8:1-4)? What about the woman caught in adultery (John 7:53-8:11)? The point is that Jesus was very merciful.
Since Jesus was merciful, and Christians are to imitate Christ, then we must also be merciful. This is reason enough for us to show mercy. However, James gives us another reason to show mercy. James states that "mercy triumphs over judgment". Instead of judging another person by what we see, we can choose to show mercy to that person. This is what Christ did. What about us? Will we choose to be merciful, instead of harsh? I hope that each and every one of us will choose to show mercy. This is what Christ did, and this is what James encourages us all to do.