1 Now it came to pass after these things that God tested Abraham, and said to him, "Abraham!" And he said, "Here I am."

2 Then He said, "Take now your son, your only son Isaac, whom you love, and go to the land of Moriah, and offer him there as a burnt offering on one of the mountains of which I shall tell you."

3 So Abraham rose early in the morning and saddled his donkey, and took two of his young men with him, and Isaac his son; and he split the wood for the burnt offering, and arose and went to the place of which God had told him. 4 Then on the third day Abraham lifted his eyes and saw the place afar off. 5 And Abraham said to his young men, "Stay here with the donkey; the lady and I will go yonder and worship, and we will come back to you."

6 So Abraham took the wood of the burnt offering and laid it on Isaac his son; and he took the fire in his hand, and a knife, and the two of them went together. 7 But Isaac spoke to Abraham his father and said, "My father!" And he said, "Here I am, my son." Then he said, "Look, the fire and the wood, but where is the lamb for a burnt offering?"

8 And Abraham said, "My son, God will provide for Himself the lamb for a burnt offering." So the two of them went together. 9 Then they came to the place of which God had told him. And Abraham built an altar there and placed the wood in order; and he bound Isaac his son and laid him on the altar, upon the wood. 10 And Abraham stretched out his hand and took the knife to slay his son.

11 But the Angel of the LORD called to him from heaven and said, "Abraham, Abraham!" So he said, "Here I am."

12 And He said, "Do not lay your hand on the lad, or do anything to him; for now I know that you fear God, since you have not withheld your son, your only son, from Me." 13 Then Abraham lifted his eyes and looked, and there behind him was a ram caught in a thicket by its horns. So Abraham went and took the ram, and offered it up for a burnt offering instead of his son.

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17 By faith Abraham, when he was tested, offered up Isaac, and he who had received the promises offered up his only begotten son, 18 of whom it was said, "In Isaac your seed shall be called," 19 concluding that God was able to raise him up, even from the dead, from which he also received him in a figurative sense.

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Abraham had his son, Isaac, when he was 100 years old. His wife was barren, so his birth was truly a miracle and a gift from God. Isaac was testament of God's promise to Abraham, that he would be a father to many nations.

To test Abraham's faith, God instructed Abraham to sacrifice Isaac to him (which, as you read, Abraham was perfectly willing to do). Lots of artistic iterations of this show Abraham weeping as he is bringing his son up to the mountain. However, Abraham told his servants that both he and Isaac would be returning from the mountain. He told Isaac that God would provide a lamb for the sacrifice (the ram), and even if He didn't, he was fully assured that God would raise Isaac from the dead because of His promise to Abraham. This is a beautiful narrative and fully shows why we refer to Abraham as the father of our faith.