In my essay Full Refutation of the Protestant Interpretation of John 19:30, I refuted the common Protestant interpretation of the verse and the meaning of τετελεσται.
In his book, Ancient Christian Gospels, New Testament scholar Helmut Koester argued that τετελεσαι in John 19:30 refers to the fulfilment of Scripture in light of the use of τετελεσται elsewhere in v. 28 which I have now added to my essay:
John 19:28 retains, at the same time, the reference to the fulfillment of Scripture (Jesus . . . , that the Scripture be completed, said, “I thirst,” cf.: when Jesus had received the vinegar, he said, “It is completed,” John 19:30. (Helmut Koester, Ancient Christian Gospels: Their History and Development [London: SCM Press, 1990], 230)
In a footnote for the above, Koester wrote:
In the extant text of John, this remark has a much more pregnant significance: Jesus has completed all the works he was sent to do (cf. Bultmann, Gospel of John, 675). But the tradition or source of the Gospel of John probably expressed by this phrase is that the fulfillment of the scripture had been accomplished. (Ibid., 230 n. 1)
