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Literally translated the word tetelestai means, “It is finished.” The word occurs in John 19:28 and 19:30 and these are the only two places in the New Testament where it occurs. In 19:28 it is translated, “After this, when Jesus knew that all things were now completed, in order that the scripture might be fulfilled, he said, ‘I thirst.’” Two verses later, he utters the word himself: “Then when he received the sour wine Jesus said, ‘It is finished,’ and he bowed his head and gave up his spirit.”
The word tetelestai was also written on business documents or receipts in New Testament times to show indicating that a bill had been paid in full. The Greek-English lexicon by Moulton and Milligan says this:
“Receipts are often introduced by the phrase [sic] tetelestai, usually written in an abbreviated manner...” (p. 630). The connection between receipts and what Christ accomplished would have been quite clear to John’s Greek-speaking readership; it would be unmistakable that Jesus Christ had died to pay for their sins.