God instructed Abraham.....
Genesis 22: 2 And he said, Take now thy son, thine only son Isaac, whom thou lovest, and get thee into the land of Moriah; and offer him there for a burnt offering upon one of the mountains which I will tell thee of.
God didn't want Abraham to offer Isaac, he only wanted to see if he would......
Genesis 22: 11 ¶ And the angel of the LORD called unto him out of heaven, and said, Abraham, Abraham: and he said, Here am I.
12 And he said, Lay not thine hand upon the lad, neither do thou any thing unto him: for now I know that thou fearest God, seeing thou hast not withheld thy son, thine only son from me.
On there journey to the mountain Abraham told Isaac....
Genesis 22: 7 And Isaac spake unto Abraham his father, and said, My father: and he said, Here am I, my son. And he said, Behold the fire and the wood: but where is the lamb for a burnt offering?
8 And Abraham said, My son, God will provide himself a lamb for a burnt offering: so they went both of them together.
This offering was a symbolic gesture that would mimic God's ultimate plan to save mankind. God Himself would provide a lamb without blemish and without spot. As Abraham was about to offer his only son, so God would offer his only son.......
Hebrews 11:17 It was faith that enabled Abraham, when put to the test, to offer Isaac as a sacrifice--he who had received the promises offering up his only son,
18 of whom it had been said-- 'It is through Isaac that there shall be descendants to bear thy name.'
19 For he argued that God was able even to raise a man from the dead--and indeed, figuratively speaking, Abraham did receive Isaac back from the dead.
So also God offered His only Son....
John 3:16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
A lamb without spot and without blemish...
Ex 12:5 Your lamb shall be without blemish, a male of the first year: ye shall take it out from the sheep, or from the goats:
1st Peter 1:18 Forasmuch as ye know that ye were not redeemed with corruptible things, as silver and gold, from your vain conversation received by tradition from your fathers;
19 But with the precious blood of Christ, as of a lamb without blemish and without spot:
20 Who verily was foreordained before the foundation of the world, but was manifest in these last times for you,
21 Who by him do believe in God, that raised him up from the dead, and gave him glory; that your faith and hope might be in God.
So it was necessary that Christ die for the sins of humankind, and be raised from the dead, so that death might be destroyed thru faith in Christ.......
Heb 2:14 ¶ Forasmuch then as the children are partakers of flesh and blood, he also (Christ) himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil;
So Jesus death is necessary for the redemption of humankind. He is the lamb of God that taketh away the sins of the world.......
Re 5:6 ¶ And I beheld, and, lo, in the midst of the throne and of the four beasts, and in the midst of the elders, stood a Lamb as it had been slain, having seven horns and seven eyes, which are the seven Spirits of God sent forth into all the earth.