A crucible, as most people are aware, is a vessel used to contain precious metals as they are purified and refined under intense heat. In today's Old Testament reading, the Prophet Malachi uses the image of the crucible to describe what will soon happen to the nation of Israel: A mysterious messenger will one day come and, through the intense heat of his preaching, purifying the nation of Israel of its impurities. Who is this so-called "messenger?" And how can we, as the people of the church, cooperate in God's refining work? This is what we'll explore in today's sermon on Malachi 3:1-4.