In Deuteronomy 6:4, the most important text for both ancient and modern Judaism, we read: “Hear, O Israel! The Lord is our God, the Lord is one.”
For the Apostle, the phrase “The Lord is our God” referred to the present covenantal reality for Israel as God’s ancient people; while the phrase “The Lord is One” referred to the future time when the fullness of the nations will join Israel in the worship of their God. What is striking is that Paul was not alone in his thinking. There are good reasons to see Paul’s views as representative of the views of many other Jews who were contemporaneous with him and those who would come later. Let us consider several Jewish sources that place the Apostle Paul firmly within the Jewish matrix of thought regarding this issue (For an expended treatment consult Paul and the Jewish Tradition: The Ideology of the Shema by Mark Nanos).
A commentary on the book of Deuteronomy written in the third-century states:
“The Lord, our God,” over us (the children of Israel); “the Lord is one,” over all the creatures of the world. “The Lord, our God,” in this world; “the Lord is one,” in the world to come. As it is said, “The Lord will be king over all the earth. In that day will the Lord be one and His name one.” (Sifre on Deut. 6:4)
A commentary on Deuteronomy written in the eleventh-century states:
“The Lord who is our God now, but not (yet) the God of the (other) nations is destined to be the One Lord, as it is said… ‘And the Lord shall be king over all the earth; on that day shall the Lord be One and His name One.’” (Rashi on Deut. 6:4)
The big difference between the Jews who authored the above-mentioned writings and the Apostle Paul comes down to this: Paul was convinced that time of the ingathering of the nations described in the prophets had already arrived, while other Jews were not.
The centrality of the Shema in Paul’s letters can be seen in many instances. Here are but a few representative examples.
Paul, when making an argument that while there are other gods who are loved and worshiped by other people, stated that for him and his community there is but One God.
“Therefore, concerning the eating of things sacrificed to idols, we know that there is no such thing as an idol in the world and that there is no God but one. For even if there are beings who are called gods whether in heaven or on earth, as indeed there are many gods and many lords, yet for us there is but one God, the Father, from whom are all things and we exist for Him; and one Lord, Jesus Christ, by whom are all things, and we exist through Him.” (1 Corinthians 8:4-6)
“Therefore I, the prisoner of the Lord, implore you to walk in a manner worthy of the calling with which you have been called… There is one body and one Spirit, just as also you were called in one hope of your calling; one Lord, one faith, one baptism, one God and Father of all who is over all and through all and in all.” (Eph. 4: 1-5).
Was the Shema important to Paul? No. It was central to his theology!