Why was Holling very impressed with Danny's party?

Danny Hupfer is Holling's Jewish friend. He's reached the age where he will be required to perform his bar mitzvah, the formal rite of passage into manhood for Jewish boys. Danny takes his forthcoming bar mitzvah very seriously, and prepares thoroughly for the occasion. Holling attends the ceremony, and is genuinely impressed with how Danny conducts himself under the weight of so much expectation. Danny sings, and reads from the Torah. Holling immediately understands the significance of what's happening: Danny's taking his place among a historical and religious community going back thousands of years. Naturally, Danny understands the significance of this too, which earns the admiration of Holling. Right before his very eyes, Danny turns from a boy into a man.
But Holling's father doesn't really see the point. He doesn't believe that you can become a man simply by "chanting a few prayers." He thinks that the way to do that is by getting a good job and providing for your family. But Holling admirably stands his ground, telling his father that being a man is more than about just your job; it's about having the freedom to choose for yourself.