Isaiah 43:13

Yea, before the day was I am he; and there is none that can deliver out of my hand: I will work, and who shall let it?

God existed before time began, dwelling in eternal presence where past, present, and future are alike and the most distant ages are seen as clearly as daily events.
The speaker is Jesus Christ declaring His eternal presence and Godhead under the great name given to Moses and later spoken on earth as Before Abraham was, I am.
No power can rescue anyone from His hand, and no one can prevent, stop, or hinder Him from carrying out His purpose and will.
He appoints servants to carry out His will and stands at the helm directing the work as His own, so His purpose goes forward and cannot be thwarted even by resistance, lack of workers, or Satan's power and snares.
The verse therefore calls His people to calm and complete trust in Him alone without limiting Him, looking to His wisdom alone to be saved rather than to finite human wisdom, human beings, and human strength.

Meaning and Context

Before time began God already was, existing before the day was in eternal presence for whom past, present, and future are alike, beholding the most remote past and the far distant future as clearly as daily events. The words I am he are the great name I AM given to Moses, and the same claim afterward made on earth as Before Abraham was, I am, showing that the speaker through Isaiah is Jesus Christ declaring His eternal presence and Godhead. That identity proves He lived fifteen hundred years before laying off His royal robe and crown in heaven to become a man. No power can rescue anyone from His hand and power, and when He declares I will work, and who shall let it, no one can prevent, stop, or hinder Him from carrying out His purpose and will, with let meaning hinder. He alone has power to deliver His people, and none can deliver out of His hand or prevent Him from acting.

The verse belongs to God's full revelation of His purpose for His people in Isaiah 41-45, to be prayerfully studied. That revelation directs them to look to His wisdom alone and be saved rather than turning to finite human wisdom, human beings, and human strength. In the surrounding words of Isaiah 43:8-13, this certainty rests on God's uniqueness as the Lord and Savior, God and there is none else, His past acts of declaring and saving, and His witnesses' calling to know and testify that He is God. He has redeemed Jacob and glorified Himself in Israel, blotting out transgressions as a thick cloud and calling His servant to return to Him. In the Lord alone are righteousness and strength, in whom all the seed of Israel shall be justified and shall glory.

Sovereign Work and Prophecy

The declaration that no one can rescue from His hand or stop the work He purposes to do is sovereignty over the work set before His people. He appoints servants to carry out His will, and the work cannot be thwarted despite resistance. The work is the Lord's own, and He stands at the helm directing it, so His purpose goes forward and no one can stop or hinder Him even when there is a great lack of workers of the right order with consecrated ability.

When He works, His irresistible working overthrows Satan's power and breaks Satan's snare. This holds even where Satan has stamped his own image on men, organized them as criticizers, filled them with revolt and fault-finding against the ministry and the message, and leavened the church through them. God converts such men as a miracle of mercy. By this He defeats Satan's effort to plant his throne between human worship and God and to intercept the adoration due to God by uniting human agencies to see faults, cherish criticism, accuse His servants, and make His message of none effect. The Lord can work and nothing can hinder Him amid bitter opposition in the churches, even when ministers make false statements without any truth and continue bold and determined after being exposed by those not of the faith, for He is the trust of His people and can bring such opposers to confusion.

The declaration belongs to prophecies about God's people being robbed and held captive with no human deliverer, for God alone has power to deliver His people. Those prophecies are to be fulfilled in the last days when God's law is made void, and in that time God will show His chosen people great grace. It belongs to a chapter of assurance and promises, encouraging believers facing affliction amid judgments and latter-day calamities that the Lord will certainly fulfill all He has promised.

Call to Trust

God alone has power to deliver His people, and when He acts no one can prevent His work or rescue anyone from His hand and power. He is eternal and sovereign, God before time began, and no one can hinder Him from carrying out His purpose and will. His power cannot be resisted, for there is nothing too hard for Him. His are the greatness and the power and the glory and the victory and the majesty, and His greatness is unsearchable. Therefore the Holy One of Israel must not be limited by looking to human beings and human strength, but must be trusted alone with calm, complete and perfect trust. This deliverance will be shown with great grace to His chosen people in the last days, when they are robbed and held captive and His law is made void.

The same working calls His people to look to Jesus for spiritual knowledge. The light given is not to be hidden under a bushel, but to give light to all who are in the house. For God gave His Son to be a light of the Gentiles, to open blind eyes and to bring out the prisoners from the prison and those who sit in darkness out of the prison house.