Now, CAPITALISM is compatible with Christianity, no question about it. Both ideas coexisted easily in early America.
But in Ayn Rand's own words: "I am not primarily an advocate of capitalism, but of egoism; and I am not primarily an advocate of egoism, but of reason. If one recognizes the supremacy of reason and applies it consistently, all the rest follows."
Her defense of capitalism is the END product of her philosophy, not its beginning. She defends it primarily on moral grounds, arguing that it is the only economic system compatible with either morality or human nature in general.