My mother was an only child. She wasn’t, however, born that way. Her older brother died of peritonitis in China when he was 11, and my grandparents mourned. I don’t think they ever fully healed the loss of their only son, the heir, the one who would carry on the family name.

I have seen parents grieve the loss of their children. Such a loss is unnatural, as if someone had turned the world upside-down and shaken it.

That’s what makes the story of Abraham so difficult to read. Here was a tribal chieftain, someone known and respected — but 75 years old and without an heir. God appeared to him one day, told him to leave everything he knew, and made an astounding promise:

I will make of you a great nation and will bless you. I will make your name respected, and you will be a blessing. I will bless those who bless you, those who curse you I will curse; all the families of the earth will be blessed because of you. (Gen 12:2-3, CEB)

Abraham believed and obeyed. He did need some additional encouragement along the way (e.g., Gen 15:4), but God kept his promise. To Abraham’s great joy, a son was eventually born to him and his wife Sarah. They called him Isaac, a name meaning “he laughs” (Gen 21:1-7).

But it took 25 years for the promise to be fulfilled, when Abraham was 100 and Sarah a spry 90 years old.

Twenty-five years is a long time to wait for anything.

And then, in the very next chapter, we read that God inexplicably “tested” Abraham by asking him to give Isaac back, to sacrifice him on a mountain in Moriah (Gen 22:1-2). It’s one of the most controversial stories of Genesis. Why would God do such a thing? Would Abraham still do whatever God told him, even if it was painful, even if he didn’t understand why? Would he give back the son he loved, the one he waited 25 years for, to the God who made the promise?

We don’t know how old Isaac was at this point; he probably wasn’t a small child, but there is no way to be certain. Abraham decided to trust God; I like to think that Isaac also decided to trust his father, even as he submitted to being sacrificed.

God, of course, stayed Abraham’s hand, then renewed his covenant promise: “All the nations of the earth will be blessed because of your descendants, because you obeyed me” (Gen 22:18).

Until I read the story again recently, I’d never noticed how much was at stake. To be sure, God blessed Abraham richly for his obedience: he would have descendants beyond number (Gen 22:17). But it wasn’t just about Abraham: God blessed the world through Abraham’s descendants. That was always the idea, from the very first promise: God’s people were blessed to be a blessing to others.

It’s still the idea.

…

As the apostle Peter stood at the outer edge of the temple courts, he preached boldly to the crowds. You crucified the Messiah! Repent! Turn back to God!

But it wasn’t all doom and gloom. He told them that their sins could be wiped away; that God would send relief and refreshment; that God would once again send the Messiah himself when the time was right. All of this had been foretold by the prophets. Peter wanted the people to understand themselves as part of an ancient story that was still unfolding before them.

And then, the punch line:

You are the heirs of the prophets and the covenant that God made with your ancestors when he told Abraham, Through your descendants, all the families on earth will be blessed. After God raised his servant, he sent him to you first—to bless you by enabling each of you to turn from your evil ways. (Acts 3:25-26)

You did evil by killing the Messiah. But you are the heirs of the covenant, of the promise God made to Abraham. That’s why God wants to bless you. By faith in the name of Jesus you can turn away from evil. Then you will be able to fulfill your covenant purpose: he blesses you to be a blessing.

We have hopes and dreams for ourselves and our children. Will we all be happy? Successful? Will we find love, purpose?

There’s nothing particularly wrong with any of this. But the question the Bible puts to believers is whether we are a blessing to others. God wants to bless the families of the earth, and he chooses to do that through his people.

That’s the idea. It always has been.