Background: Sacrifices to idols
Paul begins with these introductory remarks:
1 Now concerning food offered to idols: we know that “all of us possess knowledge.” This “knowledge” puffs up, but love builds up. 2 If anyone imagines that he knows something, he does not yet know as he ought to know. 3 But if anyone loves God, he is known by God. 4 Therefore, as to the eating of food offered to idols, we know that “an idol has no real existence,” and that “there is no God but one.” 5 For although there may be so-called gods in heaven or on earth—as indeed there are many “gods” and many “lords” — 6 yet for us...one God...one Lord... (1 Corinthians 8 ESV)
Paul has chosen to use a matter the Corinthians raised, food sacrificed to idols, to illustrate how yet for us one God...one Lord... is to be understood. The NIV commentary explains the issue:
8:1 Now about food. Another matter the Corinthians had written about (see 7:1). sacrificed to idols. Offered on pagan altars. Meat left over from a sacrifice might be eaten by the priests, eaten by the offerer and his friends at a feast in the temple or sold in the public market. Some Christians felt that if they ate such meat, they participated in pagan worship and that compromised their testimony for Christ. Other Christians did not feel this way.
By beginning with yet for us... Paul is making a distinction between an implied them and us, the saints in Corinth. That is, all who have received the Gospel which Paul preached (cf. 1 Corinthians 15:1). The implied them are those who rejected Paul's Gospel. Both groups, us and them consist of those whose physical ancestry would be identified as Gentiles or Jews. With respect to making and eating sacrifices to idols this diagram depicts the situation:
Jews who rejected the Gospel remain unchanged in their practice of Judaism: they do not make offerings to idols nor would they purchase or consume the left overs. Similarly, Gentiles who reject Paul's preaching continue their practice of making, purchasing, and eating the offerings. The one group who is clearly affected by the Gospel are Gentiles who believe: they have stopped making sacrifices to idols. However, as the above diagram shows, the question of the "left overs" remains.
...no God but one
Despite sharing in the rejection of Jesus as the Christ and refusing to call Him Lord, unbelieving Gentiles and Jews have very different beliefs about God. Gentiles who reject Paul's Gospel have and continue to make offerings to many gods and many lords. On the other hand, Jews who reject Paul's Gospel do not make offerings or have any part with the left overs. It violates their Law.
Despite their rejection of the Gospel, Jews claim there is no God but one:
3 But if anyone loves God, he is known by God. 4 Therefore, as to the eating of food offered to idols, we know that “an idol has no real existence,” and that “there is no God but one.”
(1 Corinthians 8)
Arguably Jews who reject the Gospel still love "God" and are known by "God." Like Christians they know idols have no real existence and they know there is no God but one. This phrase is another of parallelism:
ὅτι οὐδὲν εἴδωλον ἐν κόσμῳ καὶ
ὅτι οὐδεὶς θεὸς ἕτερος εἰ μὴ εἷς
The group Paul identifies as know there is no God but one, includes Jews who have rejected Paul's Gospel. When a Jew rejected the Gospel, they only rejected Paul's claim Jesus was the Christ, and they continued in their previous beliefs of God as found in the Scriptures. Furthermore, they do not accept Jesus as the Christ and they do not call Him "Lord" or "lord."
Yet for us...one Lord...
Paul's one God...one Lord... needs to be understood with the them-us contrast:
[unlike Gentiles and Jews who reject the Gospel] for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist.
All who reject the Gospel lack the Spirit of God and do not call Lord Jesus (cf. 1 Corinthians 12:3). This means neither unbelieving Gentiles or Jews say Lord Jesus. Instead, those who reject Jesus as the Christ continue with their previous religious practices. For the Gentiles this means offering their sacrifices to their many gods and their many lords.
Unbelieving Jews continue their practice of Judaism. They remain steadfast in rejecting anything associated with idols, and they remain steadfast in their belief there is one God who is their Lord:
4 ...Hear O Israel: the Lord our God is one Lord. (LXX-Deuteronomy 6:4 NETS)
Each group who accepts Paul's Gospel must change their previous beliefs. Gentiles must give up their belief in many gods and many lords; Jews must change their belief in the Lord.
For the believer whose ancestry was Jewish, the requirement of Lord Jesus Christ in Paul's Gospel is a profound change in the understanding of Lord in the Judaism they had been taught. The change demanded by Paul's Gospel very likely was a factor in their rejection of Jesus as the Christ. In other words, for the Jew, Paul was not saying a simple confession of Jesus as Christ was sufficient; rather Jesus must be both Lord and Christ (cf. Acts 2:36).
Conclusion: One God...
As the accepted answer shows, the literary structure of Paul's composition is clear: εἷς is in opposition to God-the-Father and to Lord-Jesus-Christ. An accurate translation should preserve the identical nature of the two expressions, and any punctuation difference is contrary to the meaning in the original text.
There are other significant elements to Paul's composition of 8:6.
- In verse 4 he says God is one; in verse 6 he reverses the order. Either Paul is making the point there is a difference or his composition is haphazard.
- He identifies one God as θεὸς ὁ πατήρ, a phrase not used in the LXX and one which is never repeated in the NT. If there is just "one" as monotheism demands, the term should be the same: there is no reason to use other terms.
Also when the Pauline corpus is considered in light of the OT, there are other aspects to consider:
- Nowhere is the term "Lord God" used.
- Paul routinely uses anthropomorphic terms such as θεοῦ πατρὸς to describe God. a practice Judaism considers wrong and avoids.
- Paul uses different terms by which the Father may be addressed. Not only is this anthropomorphic practice to be avoided, different phrases could indicate different meanings. The LXX is not everywhere considered a good translation of the Hebrew, but the translation philosophy is consistent, unlike Paul's treatment which would be considered as haphazard.
When contrasted with the Old Testament, these compositional elements are objective evidence Paul's understanding of the Lord our God is one is now quite different from what he held before believing the Gospel he preaches. This change in his understanding of the nature of God is evident by his need to introduce terms foreign to the OT to identify the Father. It is most unlikely a Jew who accepted the OT as Scripture would invent new terms for "God." If they felt there was a need to make a change, they would first make the relationship between the new term and OT explicit and they would then consistently use the new term.
There is simply no way to reconcile traditional and current Judaism's monotheism and Paul's language as the Shema clearly shows:
Hear O Israel: the Lord our God is one Lord, the Lord Jesus Christ through whom all things are and through whom we exist.
1. NIV Study Bible, Fully Revised, Revision Editors Kenneth L. Barker, John H. Stek, Walter W. Wessel, Ronald Youngblood, Zondervan, 2002, p. 2370
2. Of course the original language lacked capitalization; the difference is only in translation to English.