If God already had a system—Law, failure, repentance, remnant, repeat—why introduce the dramatic plot twist of the Incarnation? It’s a fair question, and one that thoughtful readers of Scripture eventually run into. The Old Testament rhythm seems clear enough: God gives the Law (Exodus 20), Israel fails (reliably), judgment follows (also reliably), and a remnant returns (mercifully). Rinse and repeat for centuries. So why not continue that cycle indefinitely?

Because the cycle, while functional, was never final. The Law revealed God’s standard, but it also exposed humanity’s consistent inability to meet it. As Paul the Apostle puts it in Romans 3:20, “through the law comes knowledge of sin.” In other words, the system worked—but mostly as a diagnostic tool. It showed the disease clearly; it did not cure it.

The Law Was Never the Cure—It Was the Mirror

The Law’s purpose becomes clearer when we stop expecting it to do what it was never designed to do. It defined righteousness, restrained evil, and preserved a people through whom God would act. But it did not transform hearts at scale. Jeremiah anticipated something more in Jeremiah 31:33: “I will put my law within them, and I will write it on their hearts.” That’s not an upgrade to the old system; that’s a new one entirely.

Enter Jesus. Not as a patch, but as a fulfillment. In Matthew 5:17, Jesus says He came not to abolish the Law but to fulfill it. Fulfillment here means bringing the Law to its intended goal. The sacrificial system, for instance, repeatedly addressed sin symbolically. Hebrews 10:4 is blunt: “it is impossible for the blood of bulls and goats to take away sins.” Repetition wasn’t a feature—it was a sign that something more decisive was needed.

Why the Suffering? Why Not Just Forgive?

This is where things get uncomfortable. If God is merciful, why not simply forgive without the cross? Scripture insists that God is not only merciful but also just. Sin is not merely a mistake; it is a rupture in relationship and a moral disorder that carries consequence. To “wave it away” would make justice optional and holiness negotiable.

The New Testament presents the cross as the place where justice and mercy meet. Romans 3:26 describes God as “just and the justifier of the one who has faith in Jesus.” The suffering of Jesus is not divine theatrics; it is the cost of reconciliation borne by God Himself. If that feels weighty, that’s because it is. Christianity does not claim forgiveness is cheap—only that it is freely given to those who receive it.

But Believers Still Sin—So What Changed?

A reasonable follow-up: if Jesus came to deal with sin, why do believers still sin? The New Testament does not deny this; it explains it. There is a difference between justification (being declared right with God) and sanctification (the ongoing process of becoming like Christ). Paul the Apostle admits the tension candidly in Romans 7:19: “I do not do the good I want, but the evil I do not want is what I keep on doing.”

What changed is not the immediate elimination of sin, but the basis of our standing with God and the power available to change. The Spirit, promised in passages like Ezekiel 36:26–27, is given to believers to transform from within.

“26 And I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your  flesh and give you a heart of flesh. 27 And I will put my Spirit within you, and cause you to walk in my statutes and be  careful to obey my rules.”

It’s slower than we’d like, admittedly. Sanctification tends to move at a pace that keeps us humble.

The Narrow Gate and the Unsettling Words of Jesus

Then there are Jesus’ own warnings, which you rightly noted. Matthew 7:13–14 speaks of a narrow gate, and a few finding it. A few verses later (7:21–23), many say “Lord, Lord,” and are turned away. That’s not exactly a marketing slogan.

These passages challenge superficial faith. They distinguish between profession and possession, between saying the right words and actually knowing Christ. The remnant theme does continue into the New Testament, but the basis shifts. It is no longer ethnic identity or Law-keeping; it is genuine relationship with Jesus, evidenced by trust and transformed life.

So Why Did Jesus Need to Come?

Here’s the synthesis:

• The Law reveals sin; it does not remove it.
• The sacrificial system points forward; it does not finalize atonement.
• Human effort consistently falls short; the pattern proves it.
• God’s justice requires a real answer to sin; His mercy provides it.

Jesus comes as the fulfillment of all of these threads. Not to restart the cycle, but to end it and replace it with something deeper: forgiveness grounded in His work, and transformation powered by His Spirit.

A Modest Conclusion (With Slightly Immodest Confidence)

The question, why send the Son, assumes the old system was sufficient and just needed better compliance. Scripture suggests the opposite. The system was intentionally incomplete, designed to point beyond itself. It was less a finished house and more a foundation waiting for the structure.

So why did Jesus need to come? Because without Him, we would still be diagnosing the problem with increasing clarity and solving it with decreasing success.

And while it’s true that only a remnant ultimately enters, the invitation has never been narrow in availability—only in acceptance. The gate is narrow not because God is stingy, but because surrender is.