Heidelberg Catechism

Question 40. Why was it necessary for Christ to humble himself even “unto death”?

Answer: Because with respect to the justice and truth of God, (a) satisfaction for our sins could be made no other way than by the death of the Son of God. (b)

(Click through to see scriptural proofs.)

a. Genesis 2:17

… but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die.

b. Romans 8:3-4

For God has done what the law, weakened by the flesh, could not do. By sending his own Son in the likeness of sinful flesh and for sin, he condemned sin in the flesh, in order that the righteous requirement of the law might be fulfilled in us, who walk not according to the flesh but according to the Spirit.

      Hebrews 2:9, 14-15

But we see him who for a little while was made lower than the angels, namely Jesus, crowned with glory and honor because of the suffering of death, so that by the grace of God he might taste death for everyone. 

Since therefore the children share in flesh and blood, he himself likewise partook of the same things, that through death he might destroy the one who has the power of death, that is, the devil, and deliver all those who through fear of death were subject to lifelong slavery.