While preparing a sermon on Zechariah's prophecy (Lk 1:67-80), I found this nice comment on the nature of Christ's redemptive kingship in Calvin's commentary (Lk 1:71),
Zacharias explains more clearly the power and office of Christ. And certainly it would be of little or no advantage to learn that Christ was given to us, unless we also knew what he bestows. For this reason he states more fully the purpose for which the horn of salvation was raised up: that believers may obtain salvation from their enemies. Unquestionably, Zacharias was well aware, that the principal war of the church of God is not with flesh and blood, but with Satan and all his armament, by which he labors to accomplish our everlasting ruin. Though the Church is also attacked by outward foes, and is delivered from them by Christ, yet, as the kingdom of Christ is spiritual, it is chiefly to Satan, the prince of this world, and all his legions, that the present discourse relates.
Our attention is also directed to the miserable condition of men out of Christ, lying prostrate under the tyranny of the devil: otherwise, out of his hand, out of his power, Christ would not deliver his own people. This passage reminds us that, so long as the Church continues her pilgrimage in the world, she lives amongst her foes, and would be exposed to their violence, if Christ were not always at hand to grant assistance. But such is the inestimable grace of Christ, that, though we are surrounded on every side by enemies, we enjoy a sure and undoubted salvation. The mode of expression may seem harsh, salvation from our enemies; but the meaning is obvious. No machinations or power, no wiles, no attacks will prevent our being delivered from them and saved “in the Lord with an everlasting salvation,” (Isaiah 45:17.)