According to the Book of Genesis, when God tells Abraham that he is going to be a daddy, Abraham starts rolling on the ground, doubled over from trying to stifle a loud, raucous guffaw. For her part, Sarah darts quickly behind the tent’s flap, so as not to tip off the Lord that she, too, is in hysterics.

In both instances, God promises the seemingly impossible gift of an heir. And in both instances, Abraham and Sarah laugh out loud. Why? I think the fairer question may be, Why not? Why not laugh in the face of a promise that seems so utterly preposterous? After all, don’t we sometimes laugh when things strike us as being ridiculous and absurd? When the Roadrunner and Wile E. Coyote race off the edge of a cliff, and both stand there for a moment, suspended in midair, looking at one another, until the Roadrunner points out that there’s nothing beneath Wile E. Coyote’s feet—it causes us to chuckle!

In a sense, that’s exactly what grace does. It stretches the limits of reality beyond the normal, expected boundaries. So is it any wonder that Abraham and Sarah—a couple who might well have been on the downside of their diamond anniversary—start laughing at the thought of strapping a child safety seat on the camel?

I don’t think we should begrudge Abraham and Sarah their laughter. It is part of what makes them human. Moreover, it indicates that they now realize that something extraordinary is on the loose, something so otherwise incredulous that laughter is the best—and perhaps the most faithful—thing they can do.

Personally, I have never interpreted God’s question of Sarah—“Why did you laugh?”—as a reprimand. I don’t believe God is angry with her. I think God is simply inquiring, “Why do find this so funny? Is there anything too great for the Lord?” But notice how quickly Sarah starts backpedaling. She denies that she was laughing—and mind you, she does so because she is afraid.

There may be a lesson in that for us. Far too often, fear cripples our emotions, keeping us from experiencing the fullness of joy God means to bring us. God wants to celebrate life with us; and what could be more fitting for a celebration than laughter?

Thankfully, Abraham and Sarah never stop laughing. They giggle with amusement when God first promises them a child. They chuckle with delight all the way through the pregnancy. And then, when the child finally arrives, they name him Isaac, which is the Hebrew word for—you guessed it—“laughter.”