The Parable of Joe and Ahmed

Whatever else may be said about Christianity, this much is true:

In Christianity, belief in Jesus and repentance means eventual salvation, no matter the sins committed before the repentance. Lack of belief in Jesus means eternal damnation, no matter how moral and upright you are in every other aspect of life.

Now we consider the following hypothetical:

Suppose Christianity is true, and suppose two twin brothers are born - they are identical in every way, so much so that given identical situations they will respond in identical ways (yes I know this goes against my ideas of free will, but we already assumed Christianity is true so we're clearly not operating in my philosophical system). Now suppose they are separated at birth and are taken to live in very different places: one is taken to Arkansas, named Joe, and baptized. The other is taken to Riyadh, named Ahmed, and made a Muslim. Given the religious statistics of Arkansas and Riyadh, it is quite likely that when Joe dies he will be a Christian and go to heaven, while Ahmed, being Muslim, will go to hell (if you wish to argue that Christianity saves moral Muslims, (a) it doesn't, and (b) then replace Riyadh with Chennai and Ahmed the Muslim with Vikram the Hindu - Christianity certainly doesn't save ANY Hindus).

But why was Joe saved when Ahmed wasn't, when, if their circumstances were switched, it would be the other way around? It follows that circumstances have influence over salvation, so that a person in Arkansas is much more likely to be saved than a person in Riyadh. This means that not all people are equal before God since God allows some to live in Riyadh (decreasing their chances of heaven regardless of will) and others to live in Arkansas (increasing their chances). This is not only an injustice of an unimaginable scale (since some people will be eternally tortured merely for having been the victims of baseless prejudice of God), it is also a self-contradiction of the notion that all men are equal in God's eyes and all have equal chance at salvation (which incidentally is in the Bible).

The only ways I can see around this contradiction are (a) to deny parts of the New Testament, something Christians can't really do, or (b) say that God knows who is more worthy and more likely to believe in Him and places them purposefully in Christian households - but again this goes against the logic of the parable of Joe and Ahmed (which is Christian logic, if I can call that logic) and implies that Arabs, Hindus, Jews, etc. are evil in general since God has seen fit to place them in positions where they will not be saved, i.e. it inherently implies racism. If you are indeed a Christian racist, I have nothing more to talk to you about and hope you get yourself shot or run over by a bus as soon as possible. If you are Christian and not a racist, I'm interested to hear your response to this - I'm always open to sharpening my arguments and fixing my logic (I really doubt anyone can convince me that the logic here has a fundamental flaw in it, but if you can, then props to you).

Any thoughts?