The covenant religion of the Jewish people
Judaism is the religious tradition of the Jewish people, tracing its origins to Abraham and later codified in the Torah given through Moses. It is one of the oldest monotheistic faiths and is foundational to Christianity. Christianity emerged from Judaism; Jesus and His early followers were Jewish. However, after the first century A.D., the two diverged sharply, chiefly over the identity of Jesus. The defining declaration of Judaism is the Shema: "Hear O Israel: The LORD our God, the LORD is one" (Deut 6:4). This strict monotheism rejects the Christian Trinity. The Jewish Bible is the Tanakh (what Christians call the Old Testament). In addition, Rabbinic Judaism highly regards the Talmud (oral law and rabbinic discussions). Following the destruction of the Temple in 70 A.D., Judaism transitioned from a sacrificial system to one focused on prayer, repentance, and following the mitzvot (commandments) in daily life. Mainstream Judaism denies that Jesus of Nazareth is the Messiah or divine. They expect the Messiah to be a human leader who will bring world peace, regather Israel, and rebuild the Temple. Judaism's primary focus is living a righteous life here and now according to God's covenant, rather than emphasizing individual salvation or a detailed afterlife.
Absolute belief in one unique, indivisible God, rejecting any concept of incarnation or Trinity.
The Law of Moses, containing 613 commandments. It is the central guide for moral, ritual, and civil life.
The special relationship between God and the Jewish people, beginning with Abraham, carrying a responsibility to exemplify God's law.
A future human king from David's line who will restore Israel, rebuild the Temple, and bring universal peace. Not a divine savior.
Since the Temple's destruction, atonement for sins is achieved through repentance (teshuva), prayer, and charity, rather than animal sacrifice.
This is the crux. Christianity proclaims Jesus is the long-awaited Messiah and the divine Son of God. Judaism rejects this. In Jewish eyes, Jesus did not bring the Messianic Age of universal peace described by the prophets (e.g., Isaiah 2:4). Christians believe Jesus will fulfill those prophecies at His Second Coming, and that His first coming was to deal with sin (Isaiah 53). The idea of worshiping Jesus is seen as idolatrous in Judaism; to a Christian, it is essential salvation.
Christianity's doctrine of the Trinity is anathema to Jewish theology. Jews view the Shema as declaring absolute, simple unity. Christians believe the Trinity is implicitly revealed in the Old Testament (e.g., plural pronouns for God, the Angel of the Lord, "Mighty God" in Isaiah 9:6) and explicitly in the New. For Jews, the infinite God would never become flesh; for Christians, the Incarnation is the ultimate act of God's love to save humanity.
Christianity teaches that humanity is fallen (original sin) and cannot save itself; salvation required the ultimate sacrifice of Jesus on the cross to fulfill the Torah's requirements. Judaism emphasizes that humans have both good and bad inclinations and can choose to follow God's law. Salvation (or right standing) comes through covenant faithfulness, repentance, and good deeds. Judaism is largely works/obedience-based; Christianity is entirely grace-based through faith in Christ's finished work.
Judaism adheres to the Law of Moses as eternal. Christianity teaches that Christ fulfilled the Law and instituted a New Covenant (prophesied in Jeremiah 31). Christians believe the ceremonial and sacrificial aspects of the Torah were shadows pointing to Christ (Colossians 2:17). Therefore, Christians do not generally keep kosher or Saturday Sabbath as binding laws, which can appear to observant Jews as a disregard for God's commandments.
"Jesus did not fulfill the Messianic prophecies. There is no world peace."
Explain the Christian concept of the Messiah's two comings. The Old Testament contains images of a suffering servant (Isaiah 53) and a conquering king (Isaiah 11). Jesus' first coming fulfilled the prophecies of humility and atonement for sin. The unfulfilled prophecies of world peace will be accomplished at His Second Coming. Even ancient rabbis noticed this dual theme and proposed two Messiahs; Christianity sees one Messiah with two phases of redemptive work.
"The New Testament takes Old Testament verses out of context."
New Testament authors (who were Jewish) used accepted Jewish interpretive methods of their day, recognizing that prophecies often have an immediate context and a deeper, typological fulfillment in the Messiah. For example, the virgin birth prophecy in Isaiah 7:14 had an immediate application, but a fuller meaning in Christ. Explain that Jesus unlocking the Scriptures (Luke 24) showed how the entire Old Testament story finds its ultimate resolution in Him.
"The Trinity is polytheism. God is one."
Affirm strongly that Christians believe in ONE God. Use analogies from the Tanakh: the Hebrew word for "one" in the Shema (echad) can imply a compound unity (like one cluster of grapes), rather than absolute singularity (yachid). Point to Old Testament hints of God's multi-personal nature, like the Angel of the LORD who accepts worship, or Genesis 1:26 ("Let Us make man in Our image"). The Trinity preserves God's nature as eternally loving and relational within Himself.
When speaking with Jewish friends, emphasize our shared heritage and reverence for the Hebrew Scriptures. Recognize the painful history of anti-Semitism often done in the name of "Christianity," and approach them with deep respect and love (Romans 9-11). Do not try to strip away their Jewishness; rather, present Jesus as the Jewish Messiah who fulfills the promises made to Abraham and David. Use the Old Testament sacrificial system to show our mutual need for atonement and how Jesus perfectly provided it once for all.