Is religious uniformity necessary?

I write about this here:

https://old.reddit.com/r/FreeSpeechBahai/comments/y3lx2d/how_would_the_union_of_all_its_peoples_in_one/isatc8q/

The fact is that I cannot of a society that is both religious and religiously diverse, so it seems like religious diversity will make a society secular. You might say that religious diversity will not lead to secularism as long as there is religious uniformity on the city level. But I think economic forces would tend to destroy this local uniformity (e.g. Protestant America needs yardwork labor from Catholic Mexico), until a more global uniformity is created.

The fact that Jewish culture was preserved in Europe and the Middle East may be attributed to the prohibition of money-lending in Christianity and Islam, creating an economic force for there to exist a religion without this restriction. But this incentive died now that the West is secular, so Judaism is dying too except for its most insular forms. But perhaps if a religion arose that did not have the restriction on money-lending, it would economically suffocate the insular forms of Judaism. Maybe the Amish thrive now because land is cheap, but if the dominant religion of the West had high birthrates,  this would drive up the prices of land and the Amish would perish. Before the West became secular I think there were only a few hundred Amish, so maybe the fact that they exist is precisely because the West is secular.

It's never religion that holds together groups of people. It's genetic quality that does. And the most important trait within that is intelligence; both its level and the general nature of it.

All religions have had problems in history, whether or not faced with religious diversity.  Yes insularity helps.  But a religion can be insular in a religiously diverse society, like Orthodox Jews are.  But the factors that make a religion last are hard to identify because so few religions have lasted.  Undoubtedly intelligence helps.

All religions are moral systems.

Our laws should be based on a defined moral system in order to protect us from the arbitrary decisions of our ruling classes.  

Religions and secular political ideologies are moral systems.  

Islam understands the logic of our laws reflecting our chosen moral system.  

To make Islam go mainstream in the West, non-Muslim Americans should be informed by Muslims who want Islamic governance that the First Amendment can only have been based on http://quran.com/2/256