Arguments Against Judaism: Revisiting C.S. Lewis’ Argument


“ When you are arguing against Him you are arguing against the very power that makes you able to argue at all: 
it is like cutting off the branch you are sitting on.” 

C. S. Lewis, Mere Christianity (1952)




Cutting Off the Branch: 

Why Rejecting Judaism is 

Rejecting Christ’s Own Fulfillment



Lewis’ point is that rejecting God (specifically, Christ) is self-defeating, because God is the very foundation of reason, morality, and truth. His argument is often used in apologetics to show that secularism, atheism, and moral relativism collapse under their own weight. But Lewis, as a Western thinker, does not press this argument into the Jewish context, where it becomes even more powerful.


This essay will argue that rejecting Jesus as the Messiah is not just rejecting Christianity—it is rejecting the very trajectory of Judaism itself. Judaism, in its covenantal, prophetic, and eschatological vision, was always oriented toward the arrival of the Messiah. If Jesus truly is the Christ, then to deny Him is to deny the very promise upon which Judaism stands—cutting off the branch from which Jewish theology itself grows.


1. Paul’s Testimony: Excelling in Judaism Yet Missing Its Fulfillment


Paul’s own journey is key to understanding this argument. In Galatians 1:13-14, he writes:


“For you have heard of my former way of life in Judaism, how I persecuted the church of God violently and tried to destroy it. And I was advancing in Judaism beyond many of my own age among my people, so extremely zealous was I for the traditions of my fathers.”


Paul was not just a Jew, but one who excelled in Judaism. He was an elite Pharisee, trained under Gamaliel (Acts 22:3), and blameless under the law (Philippians 3:6). If anyone understood Judaism at its highest level, it was Paul.


Yet, Paul testifies that he was missing the very thing that Judaism was pointing toward:


“But whatever gain I had, I counted as loss for the sake of Christ.”(Philippians 3:7)


This is not a rejection of Judaism but a realization that Judaism’s fulfillment had arrived in Christ. Paul argues that rejecting Christ is not faithfulness to Judaism—it is a failure to recognize its purpose.


2. The Messiah as the Center of Jewish Hope


The expectation of the Messiah is woven throughout the Hebrew Scriptures. Judaism was never just a moral system or a set of traditions—it was always an eschatological faith, looking toward a time when God’s anointed one would restore Israel and the world.


Key Messianic Themes in the Hebrew Bible:

The Seed of the Woman (Genesis 3:15) – The promise of one who will crush the serpent’s head.


The Scepter of Judah (Genesis 49:10) – A ruler who will come from Judah and to whom the nations will submit.


The Suffering Servant (Isaiah 53) – One who will bear the sins of many and be rejected by His people.


The Son of Man (Daniel 7:13-14) – A divine-human figure who receives eternal dominion.


These passages form the spiritual DNA of Judaism. They anticipate a Messianic figure who will not only restore Israel but will bring God’s reign to the whole world.


What Happens If You Reject This Fulfillment?


To reject Jesus is to reject the very foundation upon which Judaism is built. It is like studying the Torah, the prophets, and the wisdom literature—but ignoring their climactic moment.


This is exactly what Paul realized. He was excelling in Judaism, yet missing its very goal:


“For Christ is the goal (τέλος) of the Law for righteousness to everyone who believes.” (Romans 10:4)


If Christ is the goal, then rejecting Him is rejecting Judaism’s own trajectory.


3. Cutting Off the Branch: The Self-Defeating Nature of Rejecting Christ


Returning to Lewis’ metaphor, we can see how rejecting Jesus as the Messiah is not just rejecting Christianity—it is cutting off the very branch upon which Jewish theology stands.


Three Ways Rejecting Christ Undermines Judaism Itself


1. Rejecting Christ Undermines the Eschatological Hope of Judaism


If there is no Messiah, what is Judaism waiting for? 

If Jesus is not the fulfillment, then where is the promised King of David?

Post-Temple Rabbinic Judaism largely avoids eschatology because without a clear Messianic figure, the hope of the prophets is left in limbo.


2. Rejecting Christ Undermines the Torah’s Purpose


Paul argues that the Torah was given to lead Israel to the Messiah                            (Galatians 3:24).

If the Messiah has come, then continuing to follow Torah without Him is to            miss its very purpose.

The prophets constantly rebuked Israel for missing the weightier matters of         he law—rejecting Christ is the ultimate example of this.


3. Rejecting Christ Undermines Jewish Monotheism


Many Jewish objections to Christ center on His divinity.

But the Hebrew Bible already presents a complex unity within God—whether in the Memra (Word), the Shekinah (presence), or the Angel of the LORD who speaks as God.

Jesus does not break monotheism—He fulfills its mysterious depth, which          was always hinted at in the Hebrew Scriptures.


4. Paul’s Olive Tree Analogy: Grafting Back into the Root


Paul makes this argument explicit in Romans 11, where he describes Israel as an olive tree:


“Some of the branches were broken off, and you, though a wild olive shoot, were grafted in among the others and now share in the nourishing root of the olive tree.” (Romans 11:17)


Paul’s point is not replacement but restoration. The Jewish people are the natural branches, and rejecting Christ has temporarily removed some from the tree. But they are not cast off forever—they are invited to be grafted back in.


This further reinforces the idea that Christianity is not something foreign to Judaism but Judaism coming into its fullness.


Conclusion: Judaism Without Christ Is Incomplete and just as well Christ Without Judaism is incomplete


Rejecting Jesus is not faithfulness to Judaism—it is cutting off its very foundation.

The Messianic hope of the Hebrew Bible finds its climax in Christ.

The Torah’s purpose is fulfilled in Him.

The monotheistic mystery of God is revealed in Him.

The Jewish people are not cast away—they are invited to be grafted back into the olive tree through their own Messiah.


To reject Christ is not merely to reject Christianity; it is to reject the goal toward which Judaism has always been pointing. It is, as Lewis said, cutting off the branch on which one sits.


Paul saw this clearly, which is why he was willing to lose everything for the sake of knowing the true fulfillment of Judaism—Jesus the Messiah.





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