In my paper Full Refutation of the Protestant Interpretation of John 19:30, I refute the common (mainly Reformed) misunderstanding of the term "it is finished" () in John 19:30. I just added the following from W.E. Best, a conservative Reformed theologian, on the "finished" and "unfinished" aspects of Christ's salvific mission:
Salvation is finished and unfinished. The Lord’s statement on the cross in John 19:30, “It is finished,” means that it was completed, executed, concluded, finished, and accomplished. What was accomplished? Jesus Christ finished the work of offering Himself for the sins of the elect, the purpose for which God sent Him into the world: “I have glorified thee on the earth: I have finished the work which thou gavest me to do” (John 17:4). God had sent Christ into the world not to be a teacher, although He taught. He did not send Him to be a healer, although He healed. God sent His Son to give Himself, an offering for sin. He sent Him to stand in the place of those the Father had given the Son in the covenant of redemption. The Lord Jesus Christ accomplished that work.
Believers stand between Christ’s two statements: “It is finished” and “It is done” (John 19:30; Rev. 21:6). The latter statement does not occur until all things are made new (Rev. 21:5). We stand between the finished work of Calvary and making all things new.
The finished work of Christ is typified by (1) the covering of coats of skins (Gen. 3:21), (2) Abel’s more excellent offering (Gen. 4:4), (3) Noah’s sheltering ark (Heb. 11:7), (4) the offering of Isaac (Heb. 11:17), (5) the blood of the passover lamb (Ex. 12:1-14), (6) the life-giving fountain (Ex. 17:6), and (7) the serpent of brass (Num. 21:9).
The finished and unfinished works of Jesus Christ include the following things: (1) His work as Redeemer is finished, but His work as Restorer will remain unfinished until the perfection of every elect person. (2) Christ’s work as Saviour at the cross is finished, but His work as Sustainer is unfinished. Those who have been reconciled to Christ are saved or sustained by the living Christ (Rom. 5:10). “Saved” is added to “saved.” (3) His work as Atoner is finished, but His work as Advocate is unfinished. Provision is made for the sinning believer (I John 2:1). (4) Christ’s work as Sanctifier is both finished and unfinished. The elect are positionally sanctified at regeneration, progressively sanctified in their Christian lives, and shall be ultimately sanctified in the presence of Jesus Christ. (5) The Saviour’s work of putting away sin “from” the believer is finished, but His work of putting away sin from “within” the believer is unfinished. Sin was judicially put away from the elect in the death of Jesus Christ. Sin is put away from within the believer by Christ’s living at the right hand of the Father and the Holy Spirit’s living within the believer. (6) Christ’s dying to destroy sin’s penalty in the elect of God is finished, but His living to destroy sin’s power over him is unfinished. (W.E. Best, The Savior’s Definite Redemption: Studies in Isaiah 53 [Houston: W.E. Best Book Missionary Trust, 1982], 18-19)
