It isn't hard to understand. Religions have the same loyalty expectations as politics. It is merely a reflection of our species real evolution of grouping to create greater chances of survival.
However, religion is not a science, it is a club, and because it sets up social norms who we "love" is sold as a meme to the culture. Thus it sets up ideas like pre arranged marriages, fear of interracial marriages or international marriages. (marrying outside your nationality), living in a relationship outside marriage.
Those superstitions get sold as social norms because of human ignorance.
However, religion is not a science, it is a club, and because it sets up social norms who we "love" is sold as a meme to the culture. Thus it sets up ideas like pre arranged marriages, fear of interracial marriages or international marriages. (marrying outside your nationality), living in a relationship outside marriage.
Those superstitions get sold as social norms because of human ignorance.