Isaiah 51:15

But I am the LORD thy God, that divided the sea, whose waves roared: The LORD of hosts is his name.

The verse declares that the speaker is Israel's own God, the Lord of hosts who commands the armies of heaven and is worthy of trust for protection. It recalls how he divided the Red Sea at the Exodus, when its roaring waves could not stop him from delivering his people because he commands and stills them. That past deliverance is the ground for confidence that he will comfort his afflicted people, free the captives, restore them, and claim Zion as his own. His people therefore need not live in fear of oppressors, since the same mighty power will display itself to protect and release them when earthly powers threaten them with death in the coming crisis. He bears his people's burdens to give them assurance and hope and strength by grace to endure tedious affliction without murmuring.

Identity and Power

The speaker names himself Israel's God, the Lord of hosts, whose authority and protection make him worthy of trust. He is the one who commands the hosts of heaven and who commands the roaring waves of the sea. His name itself declares that universal command and covenant care.

He divided the sea before Israel in the Exodus from Egypt, making a way where roaring waves stood in the way of deliverance. Those waves could not prevent his deliverance, because he subdues them and quiets them by his power. In commanding, subduing, and quieting them he showed sovereign power over overwhelming forces.

With Isaiah 52 and Isaiah 53, the chapter shows that God has furnished fallen, sinful humanity a life-giving Saviour. That Saviour is the only hope of a life that measures with the life of God.

The chapter preserves the instruction Christ spoke when educating his church in the wilderness enshrouded in the pillar of cloud. There is shown God's covenant with the people he seeks to save and the terms of salvation. There is shown the most valuable education, which is knowing the only true God and Jesus Christ whom he has sent. There is shown how to conduct oneself in this world as a citizen of heaven.

Comfort and Future Deliverance

The chapter to which the verse belongs is one of assurance and hope, presenting the Lord as the one who bears His people's burdens and comforts them in the midst of burdens and affliction. His past act of deliverance is the ground of confidence that He can comfort His people, bring the captive exile to safety, free them, restore them, and affirm Zion as His people. Because He has such power to deliver, His people need not live in fear of their oppressors.

That same mighty power will deliver His people in the coming crisis, displaying His power, turning their captivity, and protecting and releasing them when earthly powers threaten them with death by violence or starvation. Even when they fear death by violence or starvation, they can trust Him to free them and protect them in that coming crisis. The verse is exceedingly precious because it gives assurance and hope and strength by grace to endure tedious affliction without murmuring, for the glory of the Lord.

As part of its passage, the verse is applied to rebuilding what has been ruined and restoring the foundations of past generations during a time of departure from truth and righteousness.