It is common for followers of Jesus to view Judaism as essential “background” information for understanding the Bible.
On the one hand, this is positive because gaining an awareness of the Jewish context of the Bible typically sharpens one’s understanding of the authentic message therein. However, viewing Judaism as part of the “background” of the story is problematic. Contrary to popular perceptions, the New Testament takes place in an entirely inter-Judaic environment. Jewish scholar Isaac Oliver says,
There is no Jewish background to the New Testament because this literary corpus contains what were originally Jewish documents. 
I have used the phrase “Jewish background of the New Testament” for years. It is going to take some discipline for me to root this out of my vocabulary (or at least, when I do use the term, to start explaining the assumptions that are typically behind it). I think it is an important step because the phrase “Jewish background” implies that some other religious space (other than Judaism) is in the foreground in the New Testament.
In his landmark paper titled the “The New Perspective on Paul,” Pauline scholar James Dunn interprets Paul’s words in Galatians 2:16 about justification as signaling a “transition from a Jewish Messianism to a faith which sooner or later must break away from Judaism to exist in its own terms.”  Here, Dunn affirms the Jewishness of “Messianism” (as all interpreters do). But then he makes it clear that “Messianism” must “break away from Judaism to exist in its own terms.” Consequently, Judaism is pushed to the background. I do not think that Jesus, Paul, or any of the apostles imagined that “Jewish Messianism” would ever break away from Judaism and exist on its own terms. This does not seem to be the intent of the apostolic decree recorded in Acts 15, which provided a ruling that enculturates Messianic Gentiles into Judaism and among Jews.
We need to be careful readers and listeners when the term “Jewish background” or even “Jewish foundations” is used in relation to the church and the New Testament. Frequently below the surface of that term is a deeply imbedded “replacement theology” paradigm. A vivid example of this occurred among my First Fruits of Zion colleagues not long ago involving an article published in the magazine Christianity Today (CT).
Our staff was initially delighted to learn that CT was highlighting a book that appeared to be affirming the Torah in some unusually positive ways. The name of the book is Bearing God’s Name: Why Sinai Still Matters. The author is Dr. Carmen Joy Imes, and she says some great things in this book. I loved Dr. Imes’s emphasis on “grace” in the Torah. It is positive that she is dedicated to helping Christians understand the Torah and its relevance for them today. However, when I read the review in CT, some signal words gave me a hunch that she would still be landing her plane in a “replacement-theology airport.”
The same day I read the review, I ordered the book. When I read it, sadly, I found that my gut had been correct. Most of the book strongly affirms the importance of the Old Testament for Christians. Yet, Dr. Imes reveals that replacement theology still governs her paradigm by expressing the following toward the end of the book:
Laws that were designed to keep Israel separate as an ethnic group have been set aside. This includes laws related to ritual purity, diet, and clothing … The need for a Temple has disappeared, fulfilled in Christ, and therefore sacrifices are no longer necessary … Christ is the faithful son standing in for faithless Israel … He is the covenant keeper who ushers in the new covenant. 
I agree with Dr. Imes about Christ being the faithful Son and that he ushers in the new covenant. But things take a negative turn when she says, “Christ … stands in for faithless Israel … Torah laws have been set aside … and the need for a Temple has disappeared.” While Dr. Imes affirms the “Jewish background” of the New Testament, the quote above is firmly supersessionist. It doesn’t give us something new or different from what prevailing replacement-theology viewpoints of the New Testament and Paul have given us for a long time.
When one hears the phrase “Jewish background of the New Testament,” it does not necessarily indicate a viewpoint that is moving Jesus’ kingdom vision forward. It is sad to say, but what this phrase often means is that Judaism and Torah have been relegated to the background of the Yeshua story. That was not the apostolic vision.
The apostles of Yeshua were bringing Judaism and Torah to the global foreground to welcome the nations into a unified yet diverse family alongside the Jewish people and under the kingship of Yeshua. “Jewish background” implies two separate religions. There is the “background” religion of Judaism and the “foreground” religion of “Judaism-free Christianity.” The result of this kind of thinking is division among the people of God.
I suggest that we stop using the phrase “Jewish background of the New Testament” (or at least that we nuance it when we are compelled to use it). There really is no Jewish “background” to the New Testament.
- Isaac Wilk Oliver, Torah Praxis after 70 C.E.: Reading Matthew and Luke-Acts as Jewish Texts (Tubingen, Germany: Mohr Siebeck, 2013), 4.
- James D. G. Dunn, “The New Perspective on Paul” (paper presented as the Manson Memorial Lecture in the University of Manchester, Manchester, England, 4 November 1982).
- Carmen Joy Imes, Bearing God’s Name: Why Sinai Still Matters (Downers Grove, IL: Inter-varsity Press, 2019), 180, 182.