God is not content for us just to understand the idea that nothing is too hard for the Lord (Jeremiah 32:17). He wants us to have the overwhelming joy of experiencing it. But the sometimes agonizing period between his promise and his provision can push us to the brink of what we think we can believe, as it did for Abraham and Sarah.

[This imaginative conversation takes place shortly after Genesis 17:22.]

Abram entered the tent, his eyes on the ground, his mind a world away. He was breathing hard. Sarai was repairing a cloak. She watched him as he walked to the back corner and collapsed on the cushions with a sigh. She recognized the bodily weariness of a divine encounter.

“The Lord has spoken to you again, hasn’t he?”
There was a pause.
“Yes.”

It usually took Abram a while before he could talk about these encounters, so Sarai pulled her threadwork up close again where she could see. Another reminder of her aging body. But now her hands were trembling. She dropped them back into her lap. What had the Lord said?

“Ishmael!” The name pierced through Sarai like an arrow. She looked through the open flap and saw Hagar hand her son supplies to carry to the cooking fire. The boy was thirteen and beginning to look like a man. He was his father’s delight, the flesh of his flesh. But not of hers. The Lord had promised Abram offspring. But it was a deep, bewildering grief that he had granted it through Hagar, her own maidservant. And it had been her own idea.

“Sarah.”
She looked over at Abram. What had he just called her?
“Yes, I called you Sarah. The Lord has changed your name.”

The Lord spoke of her? Her heart sped with a rush of hope-fueled adrenaline.

“He changed my name? What do you mean?”
“You are not merely a princess. You will be the mother of kings.”

Sarah just stared. His words didn’t register. A childless mother of kings?

“The Lord said, ‘I will bless her, and moreover, I will give you a son by her. I will bless her, and she shall become nations; kings of peoples shall come from her’ (Genesis 17:16). Sarah, God is going to give you a son, and through him, nations.”

Sarah’s whole being staggered. She steadied herself with her left hand and cupped her mouth with her right. Tears streamed. Grief, hope, and confusion churned inside her. A child? She had tried to bury this desire and she felt fear at resurrecting it. And she was ninety. She hadn’t had a feminine cycle for years. How could this possibly…

“I know what you’re thinking. I thought the same thing. When God spoke it, it was too much to take in and I said, ‘Oh that Ishmael might live before you!’”

The familiar pain shot through Sarah.

“But God said, ‘No, but Sarah your wife shall bear you a son, and you shall call his name Isaac.’”

Isaac. Her desire now had a name. Sarah mouthed it but still had no voice.

“Yes. Because the whole idea seemed so ludicrous that I laughed to myself.”
“But… I can’t… Husband… I’m ninety years old.” Sarah began sobbing. “My body is no longer able to bear children. My time has passed.”

Abram walked over and enveloped his wife in his arms. “I know, Sarah. We are powerless to have children. Now more than ever. But if we’ve learned anything these twenty-five years it’s that our hope doesn’t rest on our power to do anything. Our hope rests on the Lord’s power. Our entire lives are built on what he’s promised. And the lives of our descendants must be built on his promises for generations before they ever occupy this land. Their survival will depend on them trusting the Lord’s promises and not their own power. Should it really surprise us that the first descendant the Lord gives us is a reminder of this?”

Sarah leaned into her husband.

“And, my precious wife, our Isaac will always remind us, and many after us, that the Lord makes us laugh at the impossible.”
“Your faith strengthens mine, Abram.”
“Abraham.”

Sarah looked up at him puzzled again.

“Yes, the Lord changed my name too.” Abraham smiled. “A mother of nations needs a father of nations, doesn’t she?”

There are times when God orders our circumstances in such a way that from a human standpoint his promises are impossible to fulfill. And if at that point we find these promises almost unbelievable, as did Abraham (Genesis 17:17–18) and Sarah (Genesis 18:11–14), what God has exposed are the boundaries of our faith — boundaries he means to expand.

Resting in the promises of God is learned in the crucible of wrestling with unbelief — seasons, sometimes long seasons, when everything hangs on believing that God “gives life to the dead and calls into existence the things that do not exist” (Romans 4:17) and there is no safety net.

If you’re in such a season, as difficult as it feels, God is being incredibly kind to you. Because such seasons are when we really learn that nothing is too hard for the Lord (Genesis 18:14). And the joy in God that results makes any agony endured not even worth comparing.

Abraham and Sarah “grew strong in [their] faith” (Romans 4:20) because God pushed them to believe more than they thought was possible. For the sake of our joy he does the same for you and me.