My opinion of Rand comes from only a general knowledge of her. From what I understand, Rand seems to oppose Marxism, but her opposition to it can only be superficial.
When the origin of morality is man, its violation and its destruction will have the same origin.
I don’t know what philosophical position Rand took regarding the U.S. Constitution, but it seems that any claim to agree with it would necessarily come from ignorance or dishonesty on her part.
I understand your position as a good Christian- it would be hard to swallow the philosophy of an avowed atheist. But Rand proposed a rational basis for morality that at it’s core is not hugely different than many Christian beliefs. Not all and certainly not some very important ones but there is more commonality than you might expect.
But you shouldn’t project your perfectly reasonable differences with Rand into the realm of Marxism. Her life was dedicated to the defeat of the Marxist philosophy.