(Found in _Isaac Asimov's Treasury of Humor_, joke #39.)
Back in medieval times, a thoroughly apocryphal story tells us, the Roman Pope was persuaded by some of his more conservative advisers to endure no longer the presence of Jews in the very heart and core of world Christianity. The Jews of Rome were therefore ordered evicted from their homes by a certain date.
To the Jews of Rome this was a great tragedy, for they knew no refuge where they might not expect worse treatment than in Rome. They appealed to the Pope for reconsideration and the Pope, a fair-minded man, suggested a sporting proposition. If the Jews would appoint one of their own number to engage in a debate with him, in pantomime, and if the Jewish representative were to win the debate, the Jews might remain.
The Jewish leaders gathered in the synagog that night and considered the proposition. It seemed the only way out but none of their number wished to volunteer to debate. As the chief rabbi said, "It is impossible to win a debate in which the Pope will be both participant and judge. And how can I face the possibility that the eviction of the Jews will be the result of my specific failure?"
The synagog janitor, who had been quietly sweeping the floor through all this, suddenly spoke up. "I'll debate," he said.
They stared at him in astonishment. "You, a cheap janitor," said the chief rabbi, "debate with the Pope?"
"Someone has to," said the janitor, "and none of you will."
So in default of anyone else, the janitor was made the representative of the Jewish community and was appointed to debate with the Pope.
Then came the great day of the debate. In the square before St. Peter's was the Pope, surrounded by the College of Cardinals in full panoply, with crowds of bishops and other churchly functionaries. Approaching was the Jewish janitor, surrounded by a few of the leaders of the Jewish community in their somber black garb and their long gray beards.
Pope faced janitor, and the debate began.
Gravely, the Pope raised one finger and swept it across the heavens. Without hesitation the janitor pointed firmly toward the ground, and the Pope looked surprised.
Even more gravely, the Pope raised one finger again, keeping it firmly before the janitor's face. With the trace of a sneer, the janitor raised three fingers, holding the pose just as firmly, and a look of deep astonishment crossed the Pope's face.
Then, the Pope thrust his hand deep into his robes and produced an apple. The janitor thereupon opened a paper bag that was sticking out of his hip pocket and took out a flat piece of matzo.
At this, the Pope exclaimed in a loud voice, "The Jewish representative has won the debate. The Jews may remain in Rome."
The janitor backed off, the Jewish leaders surrounded him, and all walked hastily out of the square.
They were no sooner gone than the church leaders clustered about the Pope. "What happened, Your Holiness?" they demanded. "We did not follow the rapid give-and-take."
The Pope passed a shaking hand across his brow. "The man facing me," he said, "was a master at the art of debate. Consider! I began the debate by sweeping my hand across the sky to indicate that God ruled all the universe. Without pausing an instant, that old Jew pointed downward to indicate that nevertheless the Devil had been assigned a dominion of his own below.
"I then raised one finger to indicate there was but one God, assuming I would catch him in the error of his own theology. Yet he instantly raised three fingers to indicate that the one God had three manifestations, a clear acceptance of the docrine of the Trinity.
"Abandoning theology, I produced an apple to indicate that certain blind upholders of so-called science were flying in the face of revealed truth by declaring the Earth was as round as an apple. Instantly, he produced a flat piece of unleavened bread to indicate that the Earth, in accord with revelation, was nevertheless flat. So I granted him victory."
By now, the Jews and the janitor had reached the ghetto. All surrounded the janitor, demanding, "What happened?"
The janitor said indignantly, "The whole thing was nonsense. Listen. First the Pope waves his hand like he's saying 'The Jews must get out of Rome.' So I point downward to say 'Oh yeah? The Jews are going to stay right here.' So he points his finger at me as if to say 'Drop dead, but the Jews are leaving.' So I point three fingers at him to say 'Drop dead three times, the Jews are staying.' So then I see he's taking out his lunch, so I take out mine."