And by that will, we have been made holy through the sacrifice of the body of Jesus Christ once for all. Day after day every priest stands and performs his religious duties; again and again he offers the same sacrifices, which can never take away sins. But when this priest had offered for all time one sacrifice for sins, he sat down at the right hand of God, and since that time he waits for his enemies to be made his footstool. For by one sacrifice he has made perfect forever those who are being made holy. (Heb 10:10-14, NIV)
Commenting on Heb 10:10-14, Albert Vanhoye wrote:
Concerning the efficacy of Christ’s sacrifice, the author not only speaks here of purification and forgiveness as being primary; he also expresses the concept of “making perfect”. The Greek word is <<τελειων>>. In the Pentateuch, the word was adopted exclusively for speaking of the consecration of the High Priest. In Hebrew, one uses a slightly strange expression to express the idea of this consecration, namely: mille yad, or literally “to fill the hands”. When a High Priest was consecrated, his hands were filled. The expression derives from the fact that during the inaugurating ceremony of the sacrificial ministry, the priest received in his hands a part of the victim to be brought to the altar, and so his “hands were filed”. The Greek translators of the Septuagint did not want to translate this expression literally; presumably they considered it too material, so instead they used the verb <<τελειων>>: “to make perfect”. In this way, they made the expression more suitable for religious acceptance. The High Priest was called, “He who has been made perfect”, <<τετελειωμενος>> (Lv 21:10; Cf. Hb 7:28).
The author of the Letter to the Hebrews believes that it is right to speak of perfection with regard to priestly consecration because the priest must be made perfect if he is to enter into relationship with God. However, the author observes that the consecration of the ancient High Priest did not correspond to this law; it did not make him perfect because it consisted in external rites which could transform no one interiorly (cf. Hb 7:11; 19; 28). Christ, however, was truly “made perfect”, not by means of inefficacious external rites but by means of existential sufferings that were offered with love (cf. Hb 2:10; 5:8-9). Furthermore, the unique offering of Christ had a double effect, that is, it had a twofold efficacy, namely: it conferred perfection on Christ and it conferred perfection on us (Hb 5:9; 10:14). In his passion and resurrection, Christ was at the same time both active and passive. He received perfection and he communicated it to us—and this perfection is a priestly perfection. As I explained, it is a perfection of the relationship of filial docility to God and fraternal compassion with us.
The statement: “By a single offering, he has perfected for all time those who are sanctified”, contains something surprising. On the one hand, it indicates something that has already been achieved. Christ has made perfect <<τελειωσεν>>. The Greek verb indicates a reality that has already been communicated. On the other hand, the phrase continues to indicate a reality that is becoming, that is, a dynamism: he has made perfect those whom he is sanctifying, <<τους ‘αγιαζομενως>>, that is, those who have not received the sanctification, albeit, progressively. It is a work in progress. These are the two aspects of our religious situation that result from Christ’s oblation. On the part of Christ, all has now been achieved: he has made us perfect. On our part, all is in a process of realization. Our sanctification continues to be achieved little by little. The author has had the audacity to place these two statements together altogether they seem to be contrasting. However, they really do correspond to our Christian situation. In this regard, theologians speak of an “already accomplished” and of a “not yet”. (Cardinal Albert Vanhoye, Christ Our High Priest: Spiritual Exercises with Pope Benedict XVI [trans. Joel Wallace; Herefordshire, UK: 2010], 120-22, italics in original, emphasis in bold added)
For a fuller discussion of Heb 10:10-14 and how it does not support common Protestant interpretations of the nature of the atonement, see, for instance, the exegesis of this pericope in the following paper: