How does Atticus explain his defense of Tom Robinson to Scout?

From the text:

This case, Tom Robinson’s case, is something that goes to the essence of a man’s
conscience—Scout, I couldn’t go to church and worship God if I didn’t try to help that man.”
“Atticus, you must be wrong…”
“How’s that?”
“Well, most folks seem to think they’re right and you’re wrong…”
“They’re certainly entitled to think that, and they’re entitled to full respect for their opinions,” said Atticus, “but before I can live with other folks I’ve got to live with myself. The one thing that doesn’t abide by majority rule is a person’s conscience.”