Well...
Christianity requires at least the belief Christ is God, and that human beings are inherently sinful, and that salvation is only through Christ, right?
Also, Christianity is an altruist doctrine.
Ayn Rand preached atheism and railed against the doctrine of original sin as well as against altruism. This seems to be inherently anti-Christian.
Not all are convinced that the Old or New Testaments teach "original sin", as taught by Catholics and Calvin. My conclusion is that the Biblical evidence does not support this teaching. Instead, I see it clearly taught that (all) individuals choose sin.
Although the end situation is the same, the doctrinal path to sin does make a difference in strange and unexpected ways. For example, look up "immaculate conception"; a doctrine used in Catholic teaching to deal with "original sin" being passed to Jesus.
Bringing this diversion back to the main topic... Rand never seems to deal
consistently with the idea of forgiveness. At one moment, Dagny is helping with full strength to perpetuate an immoral system. Yet, she deserves forgiveness and inclusion into the "Galt club" because she earned it? There are internal inconsistencies with this philosophy.
From a Christian perspective, I don't want justice given to me... according to The Law, justice means that I ought to be put to death. Which is where mercy plays an important role. Rand commits the philosophical failure she condemns most harshly, she wants to have her cake and eat it too. She wants mercy to play a role, while nobody is given anything they don't deserve.
Finally, "altruism" is a slippery concept. When I spank my child, is it not being altruistic? I take the loss of hurt feelings and drama, so that she might receive modified behavior.
Is it altruistic to give money to an addict? Clearly not.
So from my perspective, free markets easily fit into altruism. It is the best situation for everyone else. A controlled economy with "me" on top is the most selfish design. A design where I get to vote myself everyone else's money seems pretty selfish too.