Therefore, I will allot him a portion with the great, and he shall divide the spoil with the strong; because he poured out himself to death, and was numbered with the transgressors; yet he bore the sin of many, and made intercession for the transgressors. (Isa 53:12 NRSV)
Commenting on this passage and its relationship to Christ’s atonement being described as once-for-all (εφαπαξ) in the New Testament (e.g., Heb 10:10), one Old Testament scholar wrote:
Verse 12b takes the Servant’s suffering and his death together and views them as a single act or process. At the same time, however, it once again sets out the two aspects of the act—the Servant’s death is a death in shame. The first part could also be translated, ‘because he poured out his blood (nepeš) to death’. This suggests a sacrifice of expiation, corresponding to the sacrificial term ‘āšām (guilt offering) in v. 10. These two clear pointers to an expiatory sacrifice as the explanation of the meaning of the Servant’s suffering and death deserve to have particular attention given them. They are never, of course, to be taken in the sense of a revival of something corresponding to human sacrifice, although this would not have been beyond the bounds of possibility for the contemporaries of this song’s author—it was not so long ago that Jeremiah had protested against the resurgence of child-sacrifice. Instead, these pointers to the sacrificial character of the Servant’s sufferings and death are to be understood along the lines of the prophets’ criticisms of the cult. Since the suffering and death of the Servant is absolutely once for all in its character, the same holds true of the expiatory sacrifice which he offered—because it is a once for all act, it takes the place of the recurrent expiatory sacrifice, and so abolishes this. Here, of course, this is not carried to its logical conclusion. But the ἐφάπαξ of the Epistle to the Hebrews and its logical conclusions are already implicit here. Along with this, however, goes something else. If a man despised and disfigured by suffering and his death in shame and his grave with the wicked, can be explained as an expiatory sacrifice, this involves a radical desacralization of sacrifice. (Claus Westermann, Isaiah 40-66 [Old Testament Library; trans. David M.G. Stalker; London: SCM Press, 1969], 268)
For a discussion of the once-for-all nature of Christ's atonement and its implications for the theology of the Lord's Supper, especially that of the Roman Catholic Mass, see: