We typically think of the stories of Ishmael and Isaac and the struggle that ensued as a result of Abraham and Sarah’s disobedience. It is, I believe, a struggle that continues even today and is at the genesis of the ongoing problems that we see in the Middle East.

But beyond Ishmael and Isaac, Matthew actually also refers to Jesus as Abraham’s son.

This is the genealogy of Jesus the Messiah the son of David, the son of Abraham.

Matthew 1:1

Why would that be?

Matthew traces Jesus’s lineage back to Abraham because Jesus’s coming brought fulfillment to the promises that God made to Abraham. Here is what God said to Abraham all of the way back in Genesis 12:

I will bless those who bless you,
and whoever curses you I will curse;
and all peoples on earth
will be blessed through you.

Genesis 12:3

And then subsequently in Genesis 15, God says this to Abraham:

“Look up at the sky and count the stars —if indeed you can count them.” Then he said to him, “So shall your offspring be.”

Genesis 15:5

The problem, at least at that time, was that Abraham had no children. Abraham was, in fact, worried that he would need to give his entire estate to one of his servants. But God assured him that, despite his old age, he would have children, and his offspring, his descendants, would be like the stars in the sky.

As it turns out, Abraham does have even more children, even after Ishmael and Isaac, but even with all of these, they wouldn’t have necessarily been like the stars in the sky. No, that fulfillment would come through his grandchildren, and his grandchildren of his grandchildren, and so on.

So Jesus is referred to as Abraham’s son to show the lineage and connection that he had to Abraham as one of Abraham’s descendants.

Yet still, I wonder whether even these, after all of these generations and all of these descendants, would be enough to be considered like the stars in the sky. Obviously, there would be many, many people, but like the stars? That is a big number.

And what is more, we still have the first promise that God made to Abraham. How is it that all of the peoples on the earth will be blessed through Abraham?

In Jesus, this comes to pass and these promises are fulfilled. This is how:

Matthew places Jesus within the bloodline lineage of Abraham, so he is a direct descendant, but Jesus also fulfills the promise in a different way. In Genesis 15, we see a situation where God promises that Abraham’s descendants will be like the stars in the sky and Abraham believes God. He believes what God tells him, and so God “credits” Abraham with righteousness because of his belief in what God told him.

Abram believed the LORD, and he credited it to him as righteousness.

Genesis 15:6

Most people would say that we have to be a good person. We need to make ourselves righteous before God and then he will accept us. But in Abraham’s case, he was considered to be righteous as he stood before God because he believed what God told him.

That’s it. He believed and so he was declared to be righteous.

As Jesus came, he taught people that they must believe that he was – and still is! – who he said he was. As people believed, he made them righteous. He forgave their sins. He sent them away telling them to sin no longer, but first, based on their belief, just as God did for Abraham, Jesus also did for those who believed. Jesus was a son of Abraham in the sense of human lineage, but he was also the son of God, in one sense amongst many, that he made people righteous as a result of their belief in him.

Even today, Jesus makes us righteous as we stand before God based on our faith in him. Jesus continues to fulfill the promises that God made to Abraham becoming a blessing to all nations. Anyone that will place their faith in Christ, believing that Jesus took the punishment for their sin upon himself, will be made righteous. The blessing of Abraham became a blessing to all nations because of Jesus. And that blessing came to all nations because, like Abraham, we can be made righteous because of our belief.

In these ways, Jesus is a son of Abraham and we, as people who believe in Christ, become a descendant of Abraham by faith, one of the stars in the sky.