The arm of Jehovah's arising and putting on strength as in the days of old is for the redeemed of Jehovah to return and to come to Zion with a ringing shout and eternal joy (51:11). In the Bible, in both the Old Testament and the New Testament, we are told that God's people need God's redemption. This is because we as God's elect often become fallen. Whenever there is a fall, there is the need of redemption. First, we fell into sin. Humanly speaking, because we fell into sin, we may feel that we need deliverance. But legally speaking, according to God's economy, we need God's redemption to redeem us from sin. Human beings do not have such a thought because human beings do not know God's government. God's government always involves the matter of righteousness. Our falling into sin involves God's righteousness. For God to come to rescue us is not simple. Before God can rescue us, there must be a redemption that fulfills the requirements of God's righteousness.
Because God's elect in both the Old Testament and the New Testament have fallen into sin, they first need God's redemption to fulfill God's requirements. Actually, to redeem us from sin is to redeem us from God's condemnation. When we fell into sin, we immediately came under God's condemnation. Because we were sinful, we were condemned by God's righteousness. Hence, we needed something to fulfill God's righteous requirement so that we could be redeemed from God's condemnation.
Then, as God's elect, we quite often fall into some trouble. In the Old Testament the children of Israel fell into captivity. In their captivity they needed to be released. However, instead of using the word released, the Old Testament uses the word redeemed. Isaiah 51:11 begins, "Therefore the redeemed of Jehovah will return...." The word return indicates what it means to be redeemed here. To be redeemed here is to be released from captivity, after which the redeemed ones can return. Thus, to be redeemed out of a troublesome situation is another aspect of redemption.
When Israel was under Pharaoh in Egypt, they were suffering as slaves under the Egyptian tyranny. So God came in to send Moses to redeem them (Exo. 6:6). By these examples we can see that God's Old Testament people had at least three kinds of needs. First, they were under God's condemnation; second, they encountered environmental troubles; and third, they were enslaved under a certain kind of tyranny. From each of these three things they needed to be redeemed. It is the same with God's people in the New Testament.
When God redeemed Israel out of Egypt, He established an ordinance that every family had to kill a lamb and then put the blood of the lamb upon their doorposts as a mark for the angel who came to kill all the firstborn sons in Egypt (Exo. 12:3-7). When the killing angel saw that blood, he passed over that house (v. 13). The lamb that was slain was called the Passover lamb. That lamb was for the redemption of God's people out of God's condemnation.