I have addressed the multitudinous errors about Protestant theologies of salvation, including the nature of the atonement. One such article is a full-length refutation of the common eisegesis of John 19:30 and τετελεσαι (“it is finished”):
Robert Letham, who himself is a Reformed Presbyterian, in a book on the nature of the atonement, wrote the following under “Excurses: Christ’s continuing priestly work”; while one will disagree with his Reformed perspective on certain topics, his comments should give pause to more errant Protestants who grossly abuse John 19:30:
We have given close attention to the cross. Our Lord’s priestly activity, did, however, did not end there. On the third day he rose from the dead and he continues as our representative with God. His ongoing high-priestly role has a twofold aspect. Firstly, he makes intercession for us. As Aaron appeared in the Holy of Holies with twelve diadems in his breastplate, representing the twelve tribes of Israel, thus continually bringing them before the presence of God, so Jesus Christ is now at the right hand of God as our own representative. As we are united to him, so we are enabled to sit with him in heavenly places (Eph. 2:6). During his earthly ministry Jesus frequently prayed for his disciples. He prayed for Peter that his faith would not fail at the time he denied his master (Luke 22:31-32). He prayed for his whole church, that it might be protected from the evil one, and exemplify the unity of God himself in the world into which he was sending it. His intercession is directed to very specific purposes. It is not indiscriminate. He does not pray or the world but for those the Father has given him (Jn. Chapter 17).
This priestly work of intercession is said to continue after Christ’s exaltation (Heb. 7:25; 1 Jn. 2:1-2). Of what does it consist? We can immediately say what it is not. Due to his work of atonement being a completed work he is not offering his shed blood in the presence of the Father. Westcott’s view that the expression ‘the blood of Christ’ refers to the continued presentation of his life has been decisively refuted by Stibbs and others, who have demonstrated that it is always used to mean his life laid down in death. Instead, his intercession includes prayer for his church; the prayer is less a petition for a matter on which the will of God is not decisively known but ore a request concerning something that has been definitely settled. He is, after all, the Son of God. Moreover, the great turning point in the drama of redemption has already occurred. In fact, it is hard at this point to distinguish Christ’s intercession from the second aspect of his ongoing priestly work, that of benediction. The priests in the Old Testament were charged with the task of blessing the people (Nu. 6:24-27). This was Jesus’ parting action when he ascended (Lk. 24:51). Benediction involved not a pious wish that such and such blessings might be granted to the blessed but rather a declaration of a state of affairs that actually existed already. Jesus’ parting benediction is inseparably linked to his finished atonement for sins. He is conveying to his people the blessing stemming from his death on the cross. In his ascension ‘he led captivity captive and gave gifts to men’ (Eph. 4:8-10), gifts which were provided by the Holy Spirit. Indeed, the chief of these gifts was the Spirit himself whom Christ sent from the Father. On the Day of Pentecost Peter pointed out that the sending of the Holy Spirit was an action of the risen and exalted Christ (Acts 2:33-36). It was an act of benediction, whereby he sovereignly blessed his people in fulfilment of his atoning work on the cross. Therefore, all further ways in which Christ sustains and strengthens his churches (Rev. chapters 1-3), his continuing ministry to the church through the apostles (cf. Acts 1:1-2), his rulership of political affairs (Rev. 1:5; note where the overlap between his kingly and priestly functions) and his sending help to us in time of need (Heb. 4:14-16) all feature as was in which Christ blesses his church as its priest. We see again how close this is to his intercession. In fact, intercession and benediction are really two sides of the same coin. (Robert Letham, The Work of Christ [Contours of Christian Theology; Leicester: Inter-Varsity Press, 1993], 155-57, emphasis added)