What kind of King is this???

A Psalm of David. The LORD says to my Lord: “Sit at my right hand, until I make your enemies your footstool.” The LORD sends forth from Zion your mighty scepter. Rule in the midst of your enemies! Your people will offer themselves freely on the day of your power, in holy garments; from the womb of the morning, the dew of your youth will be yours. The LORD has sworn and will not change his mind, “You are a priest forever after the order of Melchizedek.” (Psalm 110:1-4 ESV)
In this description of the King of Kings, David writes something that trips us up, throws in the monkey wrench, and stops us in our tracks. The King is a priest... Our American minds rush to the thought: "What ever happened to separation of church and state?" Our critical Bible Scholar minds say: "But what about Uzziah the king, who presumptively went into the temple and was stricken by God with leprosy for his act?" How can this be, that the King could also be a priest? Can He do that?
I can remember when our oldest son was young, he said he wanted to be President and Part-Time Pastor, and we laughed within, thinking: "Sure, you do..." But yes, it's real, it's right, even required that the Messiah be both King and Priest. Who else could handle the sacrifice that would be required for the sins of the whole world? Such power, such authority cannot be entrusted to just anyone, or to anyone we know. Only one can be trusted to handle it correctly.
Of course, we object. It is hard enough to relinquish the rightful right of rule to the deserving King; it is at least as hard for us to say that we are wrong, sinful, and needy, and turn ourselves over to a priest in all honesty and trust Him with our forgiveness. If we do not entrust Him with one office, we are not likely to trust Him with the other. Is He your King, your Priest?