Hi Alex, appreciate the thoughtful engagement.

Let’s clarify a couple things.

You’re right that “Mere Christianity” isn’t an official creed or universal standard. Lewis never claimed it was. What he offered was a helpful framework: that there are essential, shared beliefs at the core of Christianity—what he called “mere” in the sense of basic, foundational. And while not everyone agrees on the full list of core doctrines, the Apostles’ and Nicene Creeds remain widely embraced by the overwhelming majority of Christians across history and denomination (Roman Catholic, Eastern Orthodox, Protestant, etc.).

Are there debates and disagreements? Of course. That’s been true since Acts 15. But disagreement doesn’t eliminate the existence of core truths. Disputes about the edges don’t mean there’s no center.

As for your examples: yes, some groups reject the Nicene Creed or the Chalcedonian definition, and those differences matter. But groups like the Jehovah’s Witnesses or Latter-day Saints also hold views of Jesus that diverge radically from historic Christianity. That doesn’t make them “just another flavor of Christianity”—it marks a departure from what Christians have historically affirmed. To say otherwise is to ignore 2,000 years of doctrinal consensus and pretend that orthodoxy was never a thing.

So, sure—“mere Christianity” isn’t perfect. It’s not a doctrinal formula. But it’s not arbitrary either. It’s a reasonable shorthand for the shared center that has united most Christians through the ages.

Appreciate the dialogue. Happy to keep it going if it’s constructive.

—Brian