Christianity is sometimes held to be a universalist religion. I think that's a flawed understanding, given the assumption in both the Old and New Testaments that people live in God-given nations.
First, let me acknowledge that Christianity is clearly not a tribal religion. The Christian God is conceived to be the God of all nations. Second, it is also clear that we are to extend the moral code of the Bible to all people, not just to those who belong to our own group.
I'd like to focus on one particular Bible passage, from a letter written by Paul to the Ephesians (3:15). The usual translation runs as follows:
For this reason I bow my knees before the Father, from whom every family in heaven and on earth is named, that according to the riches of his glory he may grant you to be strengthened with power through his Spirit in your inner being.
One interesting thing about this passage is that the word translated here as "family" is in its original Greek the word patria. Patria in modern English means "one's native country or homeland". And what did it mean to the Greeks?
According to the Expositor's Greek Testament:
The noun πατριά [patria]...means sometimes ancestry, but usually family, race or tribe, i.e., a number of families descended from a common stock, nation or people...Here the word seems to have the widest sense of class, order, nation, community.
The scholars I turned to for the definition of "patria" see it as having a wider meaning than "family" in the sense that we use the term (there is a different word in the Bible for one's household). They consider it to refer to family in a more extended sense such as a clan (think of the Scottish Highland clans who share a common surname denoting a shared ancestry or lineage) or to a tribe or nation (see here for a definition).
So Paul is writing that every extended family/clan/nation on earth is named from God the Father. What does this mean? Well, there are different interpretations, but some commentaries emphasise the idea that "patria" are divinely instituted, albeit imperfectly realised, models of community. Ellicott, for instance, defines "patria" as:
every body of rational beings in earth or heaven united under one common fatherhood, and bearing the name (as in a family or clan) of the common ancestor.He explains the passage as meaning:
The Apostle looks upon the fathers whose names they delight to bear as the imperfect representatives of God, and upon the family itself, with its head, as the type in miniature of the whole society of spiritual beings united in sonship to the Father in heaven
Another commentator writes:
God is the prototype Father; He is the archetypical Father. Every other family derives its family pattern from Him. There is a policy of Scripture that relationship to God revolves around the family. Our descent from the Father affects our nature...
...there is the idea that God formed the principle of the family as a divine institution. This is especially important in our time because of the assault on the family. The family originates in the very nature of God as Father
The Expositor's Greek Testament has this:
The sense, therefore, is “the Father, from whom all the related orders of intelligent beings, human and angelic, each by itself, get the significant name of family, community”. The various classes of men on earth, Jewish, Gentile, and others, and the various orders of angels in heaven, are all related to God, the common Father, and only in virtue of that relation has any of them the name of family. The father makes the family; God is the Father of all; and if any community of intelligent beings, human or angelic, bears the great name of family, the reason for that lies in this relation of God to it.
On this interpretation, God created the patria which are patterned on a model of community that spans both the earth and the heavens. God is the ultimate source of all the patria and the patria function in this world as a necessarily imperfect manifestation of a more perfect or ideal model of community derived from God the Father.
Where else in the Bible do we find the word "patria" being used? Well, there is Luke 2:4:
And Joseph also went up from Galilee, from the city of Nazareth, to Judea, to the city of David, which is called Bethlehem, because he was of the house and lineage of David
Here patria has been translated as lineage, but the commentary again states that the word itself means "Lineage, ancestry; a family, tribe. As if feminine of a derivative of pater; paternal descent, i.e. a group of families or a whole race." This passage is not as meaningful as the first one but is an example of ancestry or tribe being part of the cloth of human community in the Bible.
More significantly there is Acts 3:25. This is normally translated as follows:
You are the children of those prophets, and you are included in the covenant God promised to your ancestors. For God said to Abraham, ‘Through your descendants all the families on earth will be blessed.’
Here, again, the word patria has been translated by "families", even though it means a more extended family of people with a common lineage or ancestry. The King James Version opts for the word "kindreds". Meyer's NT commentary insists the translation should be "nations". Barnes writes:
The word translated "kindreds" πατριαὶ patriai denotes "those who have a common father or ancestor," and is applied to families. It is also referred to those larger communities which were descended from the same ancestor, and thus refers to nations, Ephesians 3:15. Here it evidently refers to "all nations."
So God is saying to Abraham that, through his descendants, all the nations on earth will be blessed. Why would there be mention of nations being blessed if nations are not part of the divine order?