In its' simplest, least complex definition, this word means (as translated in your KJV), "It is finished". In my lifetime, I have heard countless sermons on those three words. Powerful words, no doubt, that proclaim Christ understands His work on earth is now done. His job is completed, the sacrifice has been offered. Truly, this is an emphasis of this word.
Spurgeon says this word conveys “an ocean of meaning in a drop of language, a mere drop. It would need all the other words that ever were spoken, or ever can be spoken, to explain this one word. It is altogether immeasurable. It is high; I cannot attain to it. It is deep; I cannot fathom it. IT IS FINISHED is the most charming note in all of Calvary’s music. The fire has passed upon the Lamb. He has borne the whole of the wrath that was due to His people. This is the royal dish of the feast of love.”
But let's go deeper.
First, understand the tense of this verb - the perfect tense. As in the English language, this tense of this verb describes an action which is viewed as having been completed in the past, once and for all and not needing to be repeated. Doesn't it just make sense that this is in the "perfect sense"? I would submit it is common sense to think the King of Kings could accurately and thoroughly complete an action such that no rework would ever be required!
Second, understand this was not a theological word at the time Christ uttered it from Calvary. Rather, it was quite a common term in many areas of life. Merchants used this term as debt accounts were closed. Upon payment of your bill, the holder of the debt would write across the top - Tetelestai, Paid in Full. Paid in Full means you don't ever owe anything else on that debt - it has been cancelled through full performance of payment of all money owed. What was he paying - my sin debt, and yours. There is therefore now no condemnation to them which are in Christ Jesus Romans 5:8.
The Roman Penal system utilized this word. When a person was incarcerated, a complete list of the charges against them was posted on the exterior of their cell so there could be no doubt of why the person was in prison. When the sentence was served, the charges were taken down upon the prisoners release and given to the judge who wrote across the top, Tetelestai!
It was a common word to indicate a project had been completed or a goal had been accomplished. Workers used this word in admiration of the finished jobs. Artists admired their creations while uttering this word. Soldiers used this as a victorious chant when marching home from a successful battle. Those who were returning home as victors who had vanquished their enemies were very fond of marching to this word.
This was the last of the seven sayings from the cross. I don't suppose in His weakened state that the volume was much more than a whisper. Only those that were close to the cross heard him. Only those that were paying attention to him could have heard this word. One of those was a Centurion. A Centurion was a Roman officer that commanded, at a minimum, 100 soldiers. He would have heard this chant before. He would have recognized its' intended meaning. This word, and this Man's life had an impact on the Centurion because he too had marched home victoriously while chanting Tetelstai!
Now when the centurion, and they that were with him, watching Jesus, saw the earthquake, and those things that were done, they feared greatly, saying, Truly this was the Son of God. Matthew 27:54
