Is Christianity Simply an Extension of Judaism? (By Isaac Shim)
- Isaac Shim
- 15 minutes ago
- 4 min read
When comparing Christianity and Judaism, the two can appear strikingly similar at first glance. Both traditions affirm belief in one all-knowing, all-powerful God and share many sacred texts: the books of the Tanakh in Judaism correspond largely to what Christians call the Old Testament. Because of this overlap, it is not uncommon to hear the claim that the only real difference between Judaism and Christianity is the belief in Jesus Christ as the Messiah, or that Christianity is simply Judaism expanded to include non-Jewish believers and an additional set of scriptures in the New Testament. But is Christianity really just an extension of Judaism? Or does this claim overlook deeper distinctions between the two traditions? To answer this question, it is necessary to examine not only shared texts, but also how those texts are structured, interpreted, and lived out in religious practice.
It is important to begin by clarifying that the Jewish Tanakh and the Christian Old Testament are not identical. One immediate difference lies in their composition. In some Christian denominations, particularly Catholicism, the Old Testament includes books that are not part of the Jewish canon. The Catholic Old Testament contains forty-six books, seven more than the Tanakh, including deuterocanonical texts such as Judith, Tobit, Wisdom of Solomon, Sirach, and 1 and 2 Maccabees. These books, which recount events like the Maccabean Revolt or explore Jewish wisdom traditions, are not recognized as scripture within Judaism. While the Protestant Old Testament contains the same books as the Jewish Tanakh, differences still remain in the ordering, categorization, and interpretive frameworks applied to those texts.
Even where the contents overlap, the organization of scripture reflects distinct theological priorities. Both Judaism and Christianity share the Torah—the first five books of the Bible: Genesis, Exodus, Leviticus, Numbers, and Deuteronomy. Beyond the Torah, however, the arrangement diverges significantly. The Protestant Old Testament organizes its remaining books into historical writings such as Joshua and Judges, wisdom literature like Psalms and Proverbs, and prophetic texts including Isaiah, Jeremiah, and Ezekiel, which Christians often read as anticipations of the New Testament. By contrast, the Tanakh is structured into three sections: the Torah, the Nevi’im (Prophets), and the Ketuvim (Writings). Notably, books such as Chronicles appear at the end of the Tanakh rather than near the beginning, as they do in the Christian Old Testament. These organizational differences are not merely cosmetic; they shape how readers understand the narrative arc and theological emphasis of scripture. The same texts, placed in different contexts, invite different readings.
Beyond structure, interpretation further distinguishes Judaism from Christianity. A single verse can generate profoundly different meanings within each tradition. In Genesis 3:15, for instance, God speaks of enmity between the offspring of the woman and the serpent. Jewish interpretation typically understands this passage as symbolizing the ongoing struggle between humanity and evil. Christian interpretation, however, often reads the verse as an early messianic prophecy pointing to Jesus Christ—his suffering represented by the wounded heel and his victory over sin by the crushed serpent.
This interpretive divide becomes even more pronounced in passages such as Isaiah 53. Christians frequently read the “suffering servant” described in the chapter as a prophetic portrayal of Jesus’s crucifixion and sacrificial death. Jewish interpretations, however, tend to understand the servant as Israel itself, suffering collectively through exile and persecution, or in some readings, as a historical figure such as Moses. These differing interpretations demonstrate that Christianity does not merely adopt Jewish scripture unchanged; rather, it re-reads those texts through a fundamentally different theological lens. Such divergence complicates the idea that Christianity is simply Judaism with an added belief in Christ.
Differences also emerge in how scripture is emphasized and encountered in communal worship. Biblical scholar Amy-Jill Levine notes that in Judaism, “the Torah is read in its entirety in synagogues either annually or triennially,” and that each reading is paired with selections from the Prophets. Christianity, by contrast, structures its lectionaries differently. As Levine explains, Christian readings often focus on the Prophets in conversation with the New Testament, meaning that “Old Testament” passages are heard alongside Gospel or epistolary readings. Levine also observes that the texts themselves are experienced differently: in synagogues, scripture is traditionally chanted in Hebrew, whereas in most churches it is read in the vernacular. These distinctions influence not only what texts are read, but how communities hear and understand them.
Christianity and Judaism also differ in worship patterns and daily religious life. Judaism observes the Sabbath on Saturday, centering worship on prayer and the public reading of scripture under the guidance of a rabbi in a synagogue. Christianity, while highly diverse in practice, generally worships on Sunday and expresses devotion through a wide range of liturgical and non-liturgical forms depending on denomination. Catholic, Orthodox, and Protestant traditions differ significantly from one another, and even within Protestantism, worship practices vary widely.
Perhaps one of the most consequential differences lies in the role of Jewish law, particularly the laws outlined in Leviticus. Both traditions include Leviticus in their canon, yet they approach its commandments differently. Judaism continues to treat these laws—ritual, ethical, and dietary—as binding aspects of religious life. Observance of kosher dietary laws and Sabbath restrictions remains central to Jewish practice. Christianity, however, generally understands these laws through the belief that Jesus fulfilled them. As a result, most Christians do not observe dietary restrictions or ritual Sabbath laws, emphasizing instead moral conduct and imitation of Christ’s life. This difference in legal interpretation shapes everyday life in profoundly different ways and illustrates that the divergence between Judaism and Christianity extends far beyond shared scripture.
Taken together, these distinctions suggest that Christianity cannot be accurately described as a simple extension of Judaism. While the two traditions share historical roots, sacred texts, and theological concepts, they diverge in structure, interpretation, worship, law, and lived religious experience. To describe Christianity as merely “Judaism plus Christ” is to overlook the historical and theological complexity that defines both traditions. A more accurate understanding recognizes Christianity and Judaism as distinct religions shaped by shared origins, evolving interpretations, and fundamentally different paths of belief and practice.
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