He said, "It is finished!" And bowing His head, He gave up His spirit. John 19:30, NKJV.
In that verse we have the most important word in all the Bible. The words rendered in English as "It is finished!" are a single word in Greek--tetelestai.
The other three Gospels tell us that Jesus ended His earthly life with a "loud cry" or "loud voice," but do not indicate what Jesus said. Only John provides us with the words themselves. According to the fourth Gospel, Jesus' last words before His death were "It is finished!" "It's all done!" "It's complete!" (John 19:30).
All was finished, and Jesus knew it. But what was it that He had finished? His mission to earth. He had come to earth as God incarnate to demonstrate the love of God, live a perfect life, die for all who would believe in Him, and in the process defeat the devil and seal his doom. In short, through His death Jesus had accomplished salvation. Jesus had completed the work He came to do. Now He could go home to the Father.
As a result, "It is finished!" was not a moan or a sigh of one who had barely made it to the finish line. To the contrary, it was a shout of victory. "It is the cry," William Barclay writes, "of the man who has completed his task; it is the cry of the man who has won through the struggle; it is the cry of the man who has come out of the dark into the glory of the light, and who has grasped the crown....Jesus died a victor and a conqueror with a shout of triumph on His lips."
And that victory contains the meaning of the cross. Jesus, who had lived a sinless life, had now become the spotless sacrificial Lamb of God who in dying took away the world's sins (John 1:29).
Christ has died. But the victory has been won. He has defeated Satan and set the course of history until at the end of time when the saved will again hear the words "It is done" (Rev. 21:6) at the setting up of a new heaven and a new earth as the new Jerusalem descends from heaven to earth. (Rev. 21:1, 2).
Christ had completed His atoning work, but the reward of His followers will not be given in its fullness until He returns from heaven after preparing a place for them (John 14:1-3).
Meanwhile, as we wait we can rejoice in Jesus' accomplishments on the cross.