In other words, we are often all too eager to ask the question that the people of Israel ask in Malachi 2:17. "Where is the God of justice?" That is, "Why doesn't God show up and punish the wicked and reward the righteous?" Of course, in asking that we typically count ourselves among the righteous and therefore expect that there will be only reward for us.
In Malachi 3:1-4, God is indeed on his way. However, the messenger of the Lord reminds the people that he is not coming simply to dispense to them all of their wishes and desires. He comes as a refiner's fire and as a fuller's soap. It is Israel, God's own people, who are in need of cleansing and purification.
As the Church, we surely do look forward with great expectation to the coming of Jesus and his kingdom. We believe that it will bring the kind of peace, justice, and fullness of life for which we all long. But if we think that the coming of this kingdom will simply mean reward for us without refinement, then we have not understood Jesus' call to repentance. We too must be thrust into the flames and melted down so that all that contaminates our love for God and one another might be removed.
Lord, hold me in the fire, melt me, wash me, do whatever you have to do to to purify me until I am rid of everything that keeps me from being the beautiful and valuable creation you have made me to be.