Thanks, Andrew. And by the way, I did amend my previous post, in the light of jhimm’s correction; though ‘marginalize’ is a respectable word to be found in the OED.

John 19:29 probably is a reference to and enacting of psalm 69:21, which also draws our attention to the rest of the psalm. Not only are there further cross-references in the psalm specific to John’s gospel (eg psalm 69:9 and John 2:17), but the whole psalm obviously has relevance to Jesus in his suffering on the cross. And parts of the psalm are specifically contradicted by Jesus’s attitude on the cross (eg psalm 69:22-28; Jesus also said ‘Father forgive them’).

There is probably a lot more to be said here. But the narrative seems (to me, at least) to be a mirroring of what was happening to Jesus himself, rather than anything specifically to do with David - to whom the psalm is attributed, or to Israel in general - except as far as the persecuting enemies of David in the psalm reflect those who persecuted the prophets throughout Israel’s history, and ultimately those who persecuted Jesus himself.

The impact of tetelestai is of course to do with what Jesus meant when he spoke it - which is what many commentators have reflected on. It could mean that the suffering of psalm 69 is finished - but again, what else was the suffering in the psalm apart from a reflection to Jesus of his own suffering? This is why commentators are, to my mind, justified in ascribing significance to tetelestai as a word which sums up the completion of the process of atonement for sins (whose-ever), which Jesus was working through in his own person. This is what led Hudson Taylor to faith in Christ, through reading a book called ‘The Finished Work of Christ’, and the interpretation of the word ‘tetelestai’ in particular.

This isn’t a case of atomising works and verses, as jhimm suggests on another thread. It is, indeed, assessing what Jesus meant when he spoke it - in the light of what he was actually doing on the cross.

I still haven’t found ‘perfectly perfect’ - though it is echoed in at least one internet web commentary. (I’ll keep looking - I know it’s on my bookshelves somewhere). But there is plenty of evidence that ‘tetelestai’ had carried associations which, especially in context, make it more than a simple passive perfect tense of the verb - such as the use of the word for payment of receipts.