Q: How doth Christ execute the office of a king?
A: Christ executeth the office of a king, in subduing us to himself, in ruling and defending us, and in restraining and conquering all his and our enemies.

Psalm 110:3. Thy people shall be willing in the day of thy power, in the beauties of holiness from the womb of the morning: thou hast the dew of thy youth.
Isaiah 33:22. For the Lord is our judge, the Lord is our lawgiver, the Lord is our king; he will save us.
1 Corinthians 15:25. For he must reign, till he hath put all enemies under his feet.
Acts 12:17. But he, beckoning unto them with the hand to hold their peace, declared unto them how the Lord had brought him out of the prison. And he said, Go shew these things unto James, and to the brethren. And he departed, and went into another place.
Acts 18:9-10. Then spake the Lord to Paul in the night by a vision, Be not afraid, but speak, and hold not thy peace: for I am with thee, and no man shall set on thee to hurt thee: for I have much people in this city.

Westminster Project - Francis Beattie on the Kingly and Priestly role of the Mediator