The representative or mediator that we needed could not come from anyone else and the work that he was to do could not be done by anyone else. God became man so that he could identify with and unite to us. He had to become one with us.
3) Through the incarnation, God satisfies the Law’s requirements.
Christ, the last Adam, comes to obey fully the law that we have all disobeyed. In his obedience, even unto death, Christ discharges his duty as the law-keeper. In this perfect, sinless obedience he earns sufficient righteousness to be charged to our bankrupt account.
4) Through the incarnation God reconciles us to himself.
Christ had to become man so he could bear our load (identity). But he had to be God in order that he would have the power to sufficiently pay our debt (atonement). Again Calvin is throwing strikes,
It was his task to swallow up death. Who but the Life could do this? It was his task to conquer sin. Who but very righteousness could do this? It was his task to to rout the powers of the world and air. Who but a power higher than world and air could do this?
Conclusion
Think about this: “In short, since neither as God alone could he feel death, nor as man alone could he overcome it, he coupled human nature with divine that to atone for sin he might submit the weakness of the one to death; and that, wrestling with death by the power of the other nature, he might win victory for us.”
This might be my absolute favorite paragraph in all of John Calvin’s writings. He has put his finger on something glorious hasn’t he?
This Christmas season don’t let yourself or your friends settle for any consideration of the incarnation that does not bring some degree of marvel. Christ did not come to unite his divinity to humanity in order that we would be underwhelmed by him. May it never be! Consider the glorious beauty, humility and power of the incarnation. Like Melanchthon, you will never outrun its profundity in this life even as it makes you long for the age to come!
Calvin quotes from Institutes for the Christian Religion Book 2, Chapters 12-15
