Origins of religious tolerance in the West. The reasons no longer exist in the West and never did elsewhere.

 Univ. of Houston professor Gerald Horne pointed out that religious tolerance adopted during the American Founding was for the need for white solidarity in a slave society. 

Horne points out that Americans were hardly progressive, but had adopted this one idea, religious tolerance, which is really an anomally from the general thinking of the American Founders. Professor Horne points out that if you live in a county where slaves outnumber whites, maybe by 2 or 3 or 4 to 1, you can’t afford to have religious division. Slavery was a major part of the American colonies. When facing possible attacks by Indigenous who are resisting their dispossession of the land, you can’t have religious division among the whites.

From his paper:

Monthly Review, April 2020, “Delusions of the American Revolution: Science & Society looks at “The Apocalypse of Settler Colonialism.”

I am not saying you have to agree with everything Horne states, but religious conflict would had made slave societies in the South extremely difficult to sustain. The religious faction being suppressed would at the final moment of desperation would have turned to the slaves. The British had recruited slaves during the American Revolution and it was adverse to the revolutionary military effort of the colonists to the point that Gen. George Washington, with great reluctance, decided to recruit slaves. Quoting from the article. 

Horne shows that the eclipse of religion as an axis of differentiation in the settlement colonies served the purpose of uniting Europeans of all religions against enslaved Africans and indigenes. Those who applaud the century’s religious tolerance “confused a measure designed to gain an adequate racial supply with intentional avant-garde thinking” (112). The celebration of the American Revolution as a “novel display of patriotism” and “a great leap forward for humanity” is seen as a delusion; instead Horne characterizes the “revolution” as a “naked grab for land, slaves, and profit” (67).

https://monthlyreview.org/press/delusions-of-the-american-revolution-science-society-looks-at-the-apocalypse-of-settler-colonialism

If you think of the Europeans involved in colonial conquests, they can’t afford religious division either when their small armies have to occupy large territories with large populations. If the British had internal religious conflicts and also were planning an anti-Muslim and anti-Hindu campaign, their armies would have never been able to occupy and subdue India. A religious civil war in Britain would surely result in the return of British military forces to Britain, or the losing religous faction would surely make alliances with subjugated colonial populations.

The European empires of the have long since vanished except for the Russian occupation of Siberia. The United States no longer has slaves or a frontier with military conflict with Indigenous peoples. The historical and political forces driving the wide spread support of religious tolerance no longer exists.

We can see what Christianity will likely become world wide by observing Christianity in South Korea where it exists outside Western society. South Korea has a problem of Christians carrying out arson attacks on Buddhist temples. It waged campaigns of destruction against Korean shamans.