The consequences the heated discussion that Rabbi Binder has with Oscar is that the rabbi’s words drive Oscar to run to the roof of the building and threaten to jump off. With this move, Oscar takes the upper hand with the rabbi and can force him and the others to do as he commands. Oscar obtains negotiating leverage.
Before the event that forces Oscar to the roof, Oscar had legitimately been interested in having the rabbi resolve the issue for him of why the Immaculate Conception would not be possible for an all-powerful G-d.
The rabbi calls Oscar’s mother, who slaps Oscar across the face for talking back to the rabbi when, in reality, Oscar has intellectual curiosity that he wants the rabbi to address. In the next class, Oscar asks the rabbi his question again. The rabbi is at a loss for how to answer Oscar when Oscar asks in front of the other students,
Why can’t He make anything He wants to make!
When the rabbi fumbles for words, Oscar realizes that the rabbi cannot respond to his question because he has no answer. Oscar shouts at the rabbi,
“You don’t know! You don’t know anything about God!”
The rabbi spun back towards Ozzie. “What?”
“You don’t know—you don’t—“
“Apologize, Oscar, apologize!” It was a threat.
Then, just as Oscar’s mother had done, the rabbi slaps Oscar across the face. This is too much for the boy. Oscar runs out of the classroom and makes his way to the roof. There, he threatens to jump off the roof. He comes threateningly close to the edge and flaps his arms as if to fly off the building. The rabbi is horrified and orders the boys, the janitor, and even the firemen who come to rescue Oscar to listen to Oscar and obey his commands. That is how Oscar forces their conversion.