Look closely at John’s purpose statement in the standard scholarly Greek text and you’ll find something you won’t see in any English Bible: a single letter sitting inside square brackets, right in the middle of the word for “believe.” πιστεύω (pisteuō) is the verb — “to believe,” “to trust” — and in this verse it appears as πιστεύ[σ]ητε, with one bracketed sigma, the Greek s. That little flagged letter is one of the most quietly consequential puzzles in the New Testament, because the handwritten copies of John genuinely disagree about whether it belongs — and the difference it makes is not small.

Without the sigma, the verb is a present subjunctive, and its natural sense leans toward ongoing action — “that you may keep on believing,” “that you may go on trusting.” With the sigma, it shifts to an aorist subjunctive, whose natural sense leans toward entering into the action, beginning it — “that you may come to believe,” “that you may come to faith.” One letter, two different verbs of believing.

Sit with what that does. If John wrote come to believe, he wrote as an evangelist — for people who don’t yet believe, to bring them to faith for the first time. The book aims outward, at outsiders. But if he wrote keep on believing, he wrote as a pastor — for people who already believe, to steady a faith they already have. The book aims inward, at his own community. The whole question of who John was writing for turns, in part, on whether that sigma belongs.

And the honest truth is that the scholars who produce the standard Greek New Testament could not decide. The earliest manuscripts split. Some of the oldest and most respected copies read the present, without the sigma; a wide range of other early and important manuscripts read the aorist, with it. The internal evidence doesn’t break the tie either, because elsewhere in his Gospel John uses both forms almost interchangeably in this exact kind of clause. So the editors did something they rarely do: they printed the sigma in brackets and graded their own decision a “C” — their notation for genuine uncertainty. The brackets are a confession. They mean: we cannot tell you which one John wrote.

So when you meet pisteuō in John 20:31, hear the openness the brackets preserve. The verb might be evangelistic and it might be pastoral, and a single disputed letter — printed honestly, right into the scholarly text — leaves one of the largest questions you can ask about a book quietly, deliberately open.