Why it was necessary for God to have a redemption plan?

Answer 1

According to The Bible (specifically Genesis), Adam and Eve (the first humans) sinned against God and fell from grace, developing a sin nature. Christians believe that human beings are now naturally sinful and incapable of reconciling themselves back to God. Therefore, in order to be saved from hell, God would have to be the one to reconcile the human race back to Himself, for His glory.

Additional Comments:

The two divine beings of the God Family knew before the foundation of the world that man would choose to severe the close relationship God desired of His future potential children. He is also fully aware of Satan or the god of this age and how much he hates mankind and will do all he can to see us suffer and die/kill to attempt to prevent us from becoming Children of God. But God has a Plan and nothing and no one can stop that Plan from being fulfilled (Ecclesiastes 3:14).

We can know God's Plan as He always tells us all things He will do before actually doing it (Amos 3:7). It required a blood sacrifice of a 'perfect' human being, Jesus Christ (see John 3:16; Romans 3:25). This is demonstrated to us by the Feast of Passover. And the other six Annual Holy Days of God's Plan for the Salvation of Mankind are found in the Bible in Exodus 12. An important note: All Sabbaths - weekly and annual - belong to the Lord and not any one group of mankind:

Exodus 12:11New King James Version (NKJV)

11 And thus you shall eat it: with a belt on your waist, your sandals on your feet, and your staff in your hand. So you shall eat it in haste. It is the Lord's Passover.

Answer 2

Christian Answer

Because none of us are righteous and we cannot live this life on our own strength. "The wages of our sin is death" and "our righteous acts are like filthy rags" Romans 6:23 and Isaiah 64:6. Jesus came to free us from our sin by dying and rising to new life so that we may have eternal life through Him!

Jewish Answer

The Redeemer in the Jewish conception is God himself, not the Messiah. Therefore, the necessity of a Redeemer in the Jewish conception is that mankind is not powerful enough or righteous enough on its own to bring about the flourishing of the Messianic Age. The Messiah's existence, which only God can provide, is a necessary ingredient of this better Messianic Age where there is no strife or polemic. Therefore, mankind needs Divine Redemption.