Atticus Finch is a good father to his two children because he gives them a good moral center. Even though he has no wife to help him raise them, he makes sure to have a strong female role model for them in Calpurnia.
Unlike most of the citizens of Maycomb, Atticus does not discriminate on the basis of race or social class. He treats Water Cunningham as a gracious guest, even though he is both poor and only a little boy. He treats Tom Robinson like a human being, and does his best to defend him.
While Walter piled food on his plate, he and Atticus talked together like two men, to the wonderment of Jem and me. (ch 3)
Atticus's gracious and respectful treatment of Walter is mirrored in his requiring his children to treat the Radleys, especially Boo, with respect. He does not allow them to make fun of the family.
Atticus teaches his children empathy. He shows them that they have to look at things from another person’s point of view the really get along with the person, “until you climb into his skin and walk around in it” (ch 3). This is an important skill to learn, because it helps them treat others right.
Atticus also teaches the children about courage. When Jem attacks Mrs. Dubose’s flowers after she insults Atticus for defending Tom Robinson, Atticus has Jem go to her house to read to her. He tells Jem that he wanted him to see what real courage is.
It's when you know you're licked before you begin but you begin anyway and you see it through no matter what. You rarely win, but sometimes you do. (ch 11)
This is an important lesson, because he tells his children not all courage is physical. Braving an angry mob or a mad dog is courage, but so is standing up for what you believe in.
Finally, he teaches his children persistence. Even though Atticus cannot win the trial because Tom Robinson is black, he tries anyway.
"Simply because we were licked a hundred years before we started is no reason for us not to try to win," Atticus said. (ch 9)
Atticus tells his children that he could not ask them to mind him if he did not defend Robinson, and he would not be able to hold his head up. Sometimes you have to do things you don’t want to do. It is doing those things that builds character and makes you a good person.