Redemption is a two-fold thing. There is redemption by price, and redemption by power. This is beautifully set forth typically by God's deliverance of the children of Israel from Egypt. The Israelites were sealed by blood and kept from the judgment of God. Then God stretched out his mighty arm and redeemed them from the bondage of Egypt.
The Lord Jesus Christ paid the price of our redemption at Calvary. God demanded a perfect righteousness. Therefore, our Savior assumed our nature. As a man he became subject to the will and law of God in every point working out a perfect righteousness as our Representative. But that was not enough. Divine Justice demanded a full payment and satisfaction for our transgressions. This could only be accomplished by the death of the sinner. Therefore, "God made Christ to be sin for us." And in holy justice the Son of God died in our place upon the cross. God's righteousness and justice were fully satisfied. The price of our redemption was Christ's precious blood. Only by the payment of that price can God both be just and the justifier of the ungodly.
But still his people were under the bondage of sin. We were still under the tyranny of the law. We were still in captivity to Satan and our own lusts. There must also be a Redemption by Power. This redemption by power is the new birth. It is accomplished by our Lord Jesus Christ, through the operation of the Holy Spirit. At God's appointed time he sends forth the Spirit of his Son into the hearts of his people, that they might receive the adoption of sons. Mark it down as a sure fact - Every soul that Jesus Christ redeemed by the price of his shed blood, he will also redeem by the power of his right arm.
Both are essential to salvation. We must have a suitable Substitute, to redeem us with the price of his own blood. And we must have a Sovereign Deliverer, to redeem us with the power of his right arm. By virtue of his shed blood, Jesus Christ sets the prisoner free. Let us give praise to our merciful Redeemer.