In Ch. 10

Jem sees Atticus as a gentleman because of his humility..... he doesn't draw attention to himself. In learning that his father was a crack shot, Jem realized that Atticus was "good" at things...... he just didn't brag about them, and in Jem's eyes, that made Atticus the finest of gentlemen.

Jem picked up a rock and threw it jubilantly at the carhouse. Running after it, he called back: “Atticus is a gentleman, just like me!”