I had song practice this morning for Easter tomorrow. During the opening prayer of the practice session, I thought I heard the person praying "it was finished" referring to the finished work of Christ. I may have misheard it but it has again reminded me of the Greek word I learnt some years ago, were the tense is of utmost importance, in that we say "It is finished" and not otherwise.
I shall quote from William D. Mounce's Basics of Biblical Greek, Zondervan, 1993, p.218:
It is often the very first and the very last thing we say that is the most important, or the statement that is the most memorable. First impressions and last impressions are the lasting impressions. The same is true for Jesus. The first statement we hear him say is that he should be in his Father's house (Luke 2:49). Even at the age of twelve, he was aware of his divine lineage.
And as he hung on the cross, having lived a sinless life, having paid the penalty for your sins and mine, Jesus uttered his last words before dying. Tετέλεσται. "It is finished" (John 19:30). This one word summary of Jesus' life and death is perhaps the single most important statement in all of Scripture. The word means "to complete," "to bring to perfection." Jesus has fully done the work God the Father sent him to do. Paul spends Romans 5 discussing this very fact, that our salvation is sure because Christ's death totally defeated the effects of Adam's sin, completely.
But the tense of the verb, the "perfect" tense, bring out even more of what Jesus was saying. The [Greek] perfect describes an action that was fully completed and has present-day consequences. Jesus could have used the aorist, ἐτέλησεν [etelesen], and simply said, "The work is done." But there is more, there is hope for you and for me. Because Jesus fully completed his task, the ongoing effects are that you and I are offered the free gift of salvation so that we can be with him forever. Praise the Lord. Tετέλεσται. (Emphasis mine.)