Other than Tom Robinson and his family, Atticus had the most to risk by defending Tom in the rape trial. Atticus was easily putting his reputation on the line, the respect he had from the town people, and the safety of Scout and Jem in order to do what he thought was right. Atticus definitely thought it was worth the risk, so much so that he even protected Tom from the lynch mob the night Tom was transferred to the Maycomb County jail.
After classmates harassed Scout and Jem for Atticus defending Tom, he told Scout and Jem that if he didn’t defend Tom, he couldn’t ever tell them what to do and that he wouldn’t expect them to believe what he told them was right. He felt that Tom deserved a fair trial like any man, and he was the one man who could possibly make a difference and get Tom acquitted. In Chapter 11, Atticus says that his conscience told him that he must defend Tom when he tells Scout,
"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....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."
So, Atticus risked his own morality if he chose not to take the case. In the end and despite the horrific consequences, Atticus did do his best. That is why the blacks observing the trial in the segregated balcony section stood up when Atticus passed. They knew that he had given up a lot and that he did the best any man could have done to save Tom Robinson.
Atticus would probably believe that his moral values and beliefs were more important than his name or reputation, and that it was worth the risk to defend Tom Robinson in order to fight racial injustice.