An example of Atticus being honest is when he tells Scout that he is not going to win the case.
When Scout is trying to understand why Atticus’s defense of Tom Robinson is so contentious, she asks him if he is going to win the case.
"Atticus, are we going to win it?"
"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 believes that Scout should know how he feels, and should also learn a lesson about perseverance and standing up for what you believe in.
Atticus is honest because he tells his children the truth, even when he would rather they did not know it. He believes that you should tell children the truth. He explains this philosophy to his brother, Jack.
"Jack! When a child asks you something, answer him, for goodness' sake. But don't make a production of it. Children are children, but they can spot an evasion quicker than adults, and evasion simply muddles 'em.” (ch 9)
Atticus feels that children are better off when adults don’t talk to them like children. He does not talk down to his kids, and while he sometimes use lawyer speak that they don’t understand, he always explains.