Sēmeron is the ordinary Greek word for "today." It would be unremarkable if it did not sit in the middle of one of the most contested sentences in the New Testament: Luke 23:43, Yeshua's word to the thief on the cross. The Greek manuscripts have no punctuation. Three words sit in sequence: amēn soi legō sēmeron met' emou esē en tō paradeisō — "truly, to you, I say, today, with me, you will be, in paradise." The translator decides where the comma falls.

The traditional reading places sēmeron with the second clause: "Truly I tell you, today you will be with me in paradise." This produces the doctrine of immediate post-mortem transit to heaven that most Western Christianity assumes. Move the comma one word to the right and the verse reads: "Truly I tell you today, you will be with me in paradise." Now sēmeron is part of a Semitic emphatic idiom — "amen I say to you today" — that appears throughout Deuteronomy when Moshe speaks the covenant to Israel ("I command you this day," "I set before you today," "hear, O Israel, today"). On this reading, sēmeron marks the gravity of the speech-act, not the timing of the arrival.

The textual case is not settled. Some Syriac and Aramaic manuscript traditions punctuate the sentence with the comma after sēmeron. Greek manuscripts are silent. What is settled is that the traditional reading creates a contradiction Yeshua Himself names elsewhere: He was in the grave three days and three nights (Matthew 12:40), and He told Miriam at the resurrection that He had not yet ascended to the Father (John 20:17). A theology of instant heavenward transit at the moment of death leaning the whole weight of its case on a contested comma in a single edge-case scene is a theology built on a knife's edge.