'He shall bruise your head' (Gen 3:15)

David VanDrunen is helping me see the way (even the first) Adam was both a king and a priest. For instance--

The first Adam was commissioned to exercise dominion as a king (Gen 1:26-28) and to guard the holy garden of Eden as a priest (2:15), which means that when the serpent appeared, Adam should have asserted his authority, vanquished him, and protected the holy temple of Eden. Now God announces in Genesis 3:15 that what Adam failed to do would be accomplished by one of Eve's own offspring. This offspring would assert authority over the enemy and vanquish him, inflicting not a minor blow but a mortal wound to the head. So this is the original gospel message: a Son of Adam will do what Adam should have done in the first place. A second and last Adam is coming.

--Living in God's Two Kingdoms: A Biblical Vision for Christianity and Culture (Crossway 2010), 49-50