In Jesus’ prayer on his last night, an entire two thousand years of argument hinges on one small connecting word. “That they may be one καθὼς (kathōs) we are one” (John 17:22). Kathōs is the word the English renders “just as,” or “as,” or “even as.” It’s built from two smaller pieces — kata, “according to,” and hōs, “as” — so at its root it means something like according to the way that, or in the same manner as. It sets two things side by side and says: this one, like that one. What it doesn’t do, all by itself, is tell you how alike.

That’s the whole difficulty, because kathōs has a range. At one end it means a loose comparison — “in the general way that,” “patterned on.” At the other end the lexicons note it reaches toward something tighter — “in proportion as,” “to the degree that,” “corresponding exactly.” It’s the word you’d use to say do it just like I showed you — and “just like” can mean “in the same general spirit” or it can mean “exactly, point for point.” The particle itself stays silent on the distance between the two senses.

You can feel both ends in how Jesus uses the word elsewhere. A few chapters earlier he says, “Love one another. As I have loved you, so you must love one another” (John 13:34) — kathōs, “as I have loved you.” No one hears that as a claim that our love will be equal to Christ’s, identical in depth. We hear “patterned on, take its shape from mine.” That’s the loose end. But the word can also press toward exact correspondence, and that’s the end that makes John 17:22 land like a thunderclap.

Because here Jesus uses kathōs to tie two pairs together — the Father and the Son, and the disciples — joined by one hinge. “That they may be one, just as we are one.” If you press kathōs toward “patterned on,” the disciples’ unity is a real but creaturely echo of the divine oneness, modeled on it without matching it. If you press kathōs toward “exactly as,” the disciples are being prayed into the very oneness the Father and the Son share. The word will carry either reading. It won’t decide between them.

And that’s not a frustration — it’s the discovery. Set John 13:34 beside John 17:22 and you’ve found, by hand, exactly where the grammar stops and the interpretation begins. The verse genuinely permits the loose sense and the tight sense both; neither side gets a knockout from the word alone. Kathōs puts the disciples and the Father-Son pair into one sentence and falls silent on how far the likeness goes. So the next time someone tells you “just as we are one” obviously means one thing, the honest question is the one the word itself raises: which sense of “just as” are you assuming — and does the word make you assume it?