"It's only a chicken."
"Take a chicken to the butcher's and have it killed, and no one can possibly object. But if you sacrifice a chicken in the temple of Mars, you commit a grave sin against Christ."
Marcus Tullius's broad face was set in a stubborn expression, his arms folded across his chest. "If I had known about Christ when I was stationed on the Rhine I would have prayed to him. But at the time, didn't know him. So I swore to Mars that if I survived the battle on the bridge I would make him an offering each year on the anniversary of the battle for ten years. He kept his side of the bargain, and here I stand. I can't believe Christ would want me to break my oath."
"But surely an oath to a false god can be no oath at all. Satan has no good in him, and you can owe him nothing."
"I didn't promise anything to Satan, I promised a chicken to Mars. Mars isn't Satan, though I understand now that he's not God either. And I don't see how my oath to Mars is voided just because he's not the sort I took him for at the time."