An unusual criticism of Calvinism

Calvinists of different shapes and sizes are all united on two issues:

(1) God alone chooses who will be saved

(2) We do not know the criteria by which God chooses to save some but not save others

I will also add the further condition, that

(3) Those who are saved manifest it in some way, which includes claiming to be a Christian (claiming to be a Christian is a necessary but insufficient condition for one having being elected by God)

It might be that not all Calvinists would agree with (3), and I'm sure most would grant an exception in the case of infants or the mentally ill, but for normal adults, I think almost all Calvinists would agree with (3).

I think that Calvinism could be proved to be very improbable because of (2).
Whatever God's criteria for election, it presumably isn't down to randomness. Or maybe they are; in fact, that would only further support my hypothesis. But whatever the method for God's decision of election, I posit that a basis which he does not decide upon is who one's parents are, or the geographical location of one's birth.

But if we look at the course of history, Christianity has been hugely successful in some areas in some periods, and hugely unsuccessful in others. Compare now, for example, the prevalence of Christianity in North Korea and South Korea. The number of people who would claim under any circumstances to be a Christian in NK is pretty certainly very, very low. But in SK it is very high. It would be extremely hard to deny that a larger portion of SK are part of the elect than in NK.

What are we to make of this with regards to God's choice of election? It would appear that a primary method of God's choice is where one is born. I would argue that that is one of the least possible just ways of determining who should be saved. And I'm sure that most Calvinists would agree with me. Similarly, the chance of being Christian if one's parents are Christian is much higher than if one's parents are not. Are we to say that God doesn't evaluate people on an individual basis but decides to save, "most of" this family tree, and "a few from", this family tree? Again, this would seem to be an absurd way for God to determine the elect.

Formally I suppose my argument is:

1\ God alone chooses who will be in the elect

2\ The method that God chooses who will be in the elect is not on the basis of geographical location

C\ The elect are roughly evenly spread throughout the world (1, 2)

Since C is clearly false, and is derived logically from 1 and 2 (including one or two background propositions about being born in a certain area not making you relevantly, importantly and essentially different), either 1 or 2 must be false. I posit that 2 simply must be true, and I think most Calvinists would agree with me. Therefore, they must accept that 1 is false, which defeats Calvinism.