This article seems to be saying that religions are tribal by nature because it's made up of humans, and humans are tribal by nature -- ok fair enough. But the subtext I'm getting is that people in religions are less self-aware of it than the author or the people they admire.

People being more interested in comfortable beliefs rather than true beliefs has always been a concern throughout Biblical history. But that doesn't mean it never went unchallenged.

For instance, regardless of what you think of the Bible, it's interesting that Isaiah has the following to say to Judah (emphasis mine) because it shows an ever-present problem with human nature.

    For they are a rebellious people, lying children, children unwilling to hear the instruction of the Lord;
    *who say to the seers, “Do not see,” and to the prophets, “Do not prophesy to us what is right; speak to us smooth things, prophesy illusions”*

And before someone responds with a de jure objection to say that "the instruction of the Lord" is not looking for truth, I just want to make it clear that that is out of the scope of my point. My point is that, de facto, in the context, a religious text is agreeing that it is bad to "tribe-up and truth-out."

Lastly, on a personal note, as a human Christian, I think I have the same biases to groupthink as any other person because I am human. But because Christianity has a reputation, I have found that throughout my life, I've had to work harder to really test (not validate) my beliefs because I am constantly being challenged and, ironically, often ended up more informed about both my beliefs and my interlocutors' beliefs.