My problem with Christianity is that if Christianity really is the real deal then why did god not make it obvious to all and sundry? Instead we have an estimated 4000 - 10,000 different religions in the world and with an estimated 700 deities being worshiped currently. And that is not even talking about the vast number of agnostics and atheists. If god really is the god of the Christians that they claim he is why didn't he make it indisputably clear to all? Instead the god of the Christians deliberately chose to allow humans to continue living in confusion and doubt long after Christ returned to heaven. But for what purpose?
You are assuming that it would be advantageous to humanity for God to make it more "obvious". That's not necessarily the case. The ultimate goal of human life from the Orthodox perspective is to seek union with God, to attain salvation. The universe that God created is the best possible universe that will save the most souls. He sees billions of factors that we don't see.
Think about this. The devil
knows God exists, he has zero doubt. And yet, he still rebelled against him along with a third of the angels. Because creatures with free will cannot help but become prideful. It is better to remain ignorant and to reject God than to be sure of His existence and still reject Him. In the latter case, the person's sin will be greater because he consciously rejects the truth and thus his soul will become darker. So God protects those who would willfully reject Him by making Himself only obvious to those who seek Him. The evidence we have is sufficient. Jesus Christ is by far the most documented historical figure from the ancient world. The miracles He performed are exceedingly well documented, and He also fulfilled dozens of prophecies from the Old Testament. But people have to look a bit to be convinced, and that helps train the virtue of faith, which further draws us closer to God.
Not to mention, how would God prove to us he exists with 100% certainty and still allow us free will? I can't think of any way. Even if He wrote "Jesus Christ is Lord" in the stars, some would say they are going mad, or aliens did it, or outer space is an illusion. So what evidence would it take to convince you?
The reason there are thousands of religions is because people 1) some people far from the Holy Land could feel God's presence and so did the best they could without divine revelation and formulated a religious system on their own like Laozi and his Taoism, and 2) others were tricked by the devil into worshipping demons like the Hindus. Or it's a mix of both.
Sometimes it is even more strict than that where women add social circle or sub regional criteria on top of the ethnic criteria. For example in Australia I have a Serbian friend who moved to Australia when he was 12. He has family still in Serbia and Croatia and goes to visit both countries sometimes yet he still has trouble to get a girl in Serbia or Croatia despite speaking fluent Serbian because he didn't grow up in their social circles so he is seen as an outsider.
And I have a North Macedonian friend in Australia who moved to Australia as a child (but he speaks fluent Macedonian) and multiple times he tried to go back to North Macedonia to find a girl but he still struggled because he didn't grow up in their social circles so he is seen as an outsider. .
I remember when I was in Kosovo I met an Albanian girl living in the capital Pristina but she was originally from another another city in Kosovo. Her parents would not even allow her to marry an Albanian guy from another city it had to be a guy from the same city she was from, let alone a foreigner.
Basically in Europe you have the more liberal westernized countries where girls are open to marrying foreigners but like Anglo sphere women their standards are outrageous so for example a female 6 who is 30 years old in Germany will expect to marry a tall, rich and handsome guy. Then you have more traditional countries like Kosovo and North Macedonia where beautiful young girls will marry the most loser guys imaginable (ugly, out of shape, broke, cheats, treats her bad, etc) but he has to be the same ethnicity and religion.
My hope is that there is a 3rd group of countries which are the golden ticket where there are a decent number of high quality women who are willing to marry foreigners (and have reasonable standards). My guess is countries like Belarus, Moldova, Russia, Romania, Ukraine (when the war is over), etc might fit into this third group. But I am really waiting for the opportunity to put boots on the ground to see with my own eyes if this is actually the case or not. The anecdotal evidence I keep hearing tends to reinforce this view but I cannot truly know until I experience it for myself.
I think you are right that there are roughly 3 groups of countries. You can predict the level of in-group preference by the level of genetic similarity/inbreeding between people. The most inbred people in Europe are from the Western Balkans, so they are highly focused on their own in-group and don't like outsiders. Middle Easterners are a more extreme example. Certain Americans like those in Appalachia are also very inbred due to historical circumstances.
On the other hand, the most outbred are the Dutch, but this is what led to them and other Western Europeans flooding their countries with millions of migrants and accepting woke ideology. They don't care about their own people, everyone is the same as far as they're concerned.
Then you have this group in the East that stretches from Greece and Bulgaria up to Poland and Russia. They have moderate levels of inbreeding, so they are nationalistic, but I'm guessing not so extreme as to reject people outside their social groups. So my guess is that's your sweet spot and my personal experience gives credence to this theory.
