Immaculate misconception

I once had the following conversation a December evening in a crowded, noisy bar.

“I had to go to church today, because it was a holy day,” I said.

“What?” my friend replied.

“CHURCH!” I shouted. “I HAD TO GO TO CHURCH! Today was the feast of the Immaculate Conception.”

“The immaculate what?”

“CONCEPTION!”

There was a pause while my friend thought about this. “But why is the Immaculate Conception so close to Christmas? That’s the shortest – or longest – pregnancy I’ve ever heard of.”

“What?” I said.

“WHY IS IT SO CLOSE TO CHRISTMAS?”

“Oh! No,” I replied. “It’s not the conception of Jesus. It’s the conception of Mary.”

“What?”

“MARY! THE CONCEPTION OF MARY!” I yelled. “SHE WAS CONCEIVED WITHOUT SIN!”

My friend was confused. “BUT I THOUGHT THAT MARY WAS THE ONLY…”

“No, no,” I said. “That's not what immaculate conception means. It’s not a sin for a husband and wife to conceive children. God wants husbands and wives to conceive children. But we believe that Mary was conceived without original sin.”

“What?”

“ORIGINAL SIN! MARY HAD NO ORIGINAL SIN!”

There was another pause. And then, “WHAT’S ORIGINAL SIN?”

But that was a discussion I was not prepared to handle in all caps.