In First Things, Peter Berger discusses the benefits of religious pluralism for religious faith:

“First benefit: It becomes more difficult to take a religious tradition for granted. Acts of decision become necessary”…

“Second benefit: Freedom is a great gift, and pluralism opens up new areas of freedom,” according to Berger…

“Third benefit: If pluralism is combined with religious freedom, all religious institutions become in fact voluntary associations”…

“Fourth benefit: Pluralism influences individual believers and religious communities to distinguish between the core of their faith and less central elements,” according to “The Good of Religious Pluralism.”

This would be a more specific version of two arguments made by sociologists of religion in recent years:

1. Some have argued that religion, as a whole, has positive effects on society as religious people tend to vote more, participate in more religious and civic activities, and give to others. In this argument, religion itself is made better – such as agreeing to basics about the faith rather than fighting over less essential elements – and this would presumably then help the broader society by having religious groups that are softer around the edges.
2. Competition between religious groups – made possible in the United States by freedom of religion as well as the separation of church and state – actually enhances religious life as groups compete for adherents. Berger’s argument is specifically about a kind of pluralism where religious groups can peacefully interact and enhance each other. It would be interesting to then hear him discuss places where religion is pervasive but pluralism is either tenuous (competition still happens but it is violent or state-sponsored) or nonexistent.