First, I shall chuck the idea out here that there is a fundamental difference between a belief in or even an open-ness to the notion of a supreme or spiritual being or beings and "religion".

Religions are man-made things, at best frameworks within which one seeks to codify spirituality. Unfortunately, they are exclusionary in nature, the one and true faith, the lost tribe, the saved. Join us or suffer the consequences, either in the here and now by the projection of power be it social, legal, or military, or in the hereafter by the threat of eternal damnation and torment.

Two key words; threat and eternal. The latter first, we as beings are terrified by the concept of eternity, infinity, anything without an end-point we can't wrap our heads around, be it the infinity that is the universe or the eternity that is the sleep that awaits us; the infinity of death.

The former, threat, is the basis certainly of all the Abrahamic religions. Where the groupings threaten each other with the consequences of shunning, legal marginalisation, and killing each other in the here and now as one manifestation of power (and make no mistake, religion and especially Abrahamic religion exists as a tool for the imposition of power), the threat made with respect to the hereafter is even more frightening as it applies infinity/eternity, that scariest of concepts, to non-membership. Join us and you'll be saved/chosen/sit at the right hand of/76-odd virgins/even be reincarnated. Avoid the notion of silence eternal which might even be scarier than hell's infinite torment, all to get the individual to do the bidding of the religion, traditionally a state institution, the implementation of which appears to be a goal in America at the moment what with all this notion that America was begun as a Christian nation and should be once again as long as its my (arguably odd) version of Christianity.
Being absolute historical bollocks is beside the point.

You notice there hasn't been a mention of faith, spirituality, God, the teachings of Christ, Mohammed, Moses, morals, ethics, nothing of the sort. Don't agree with us you are antisemitic, heathen, infidel; you don't agree with me. Not God. Me.

Now there is a new one, by the way, and that's atheism. Atheists annoy me because they push their creed on me with the same vehemence as the Abrahamics. Believers are believers and the atheists demand me to join them in the same way for the same reasons. Join the crusade, fight the bastards, project power. It's a man-made belief system; a religion by definition.

I don't need atheists telling me what to believe on faith any more than a bunch of Southern Baptists, Islamic fundamentalists, or Netanyahu's calling everything that doesn't suit him antisemitism. I say "on faith" because they, the atheists, offer no more evidence for a point of view than any other religion, just belittlement as being some sort of superstitious moron. Like any religion, the point of view isn't germane; it's the size of the membership and the strength and vehemence of their adherence to the will of the group or more often the leadership.

Nowhere is there a manifestation of belief, other than the belief in the superiority and righteousness of ones group over all others.

Hate and divisiveness is the goal, religion is but one tool to achieve it. This country has forgotten it was actually formed without a state religion and the first in Western Civilisation to be so formed. It was formed with the notion that you could believe and practice whatever you liked as long as it didn't infringe on the next guy believing and practicing whatever he chose. Not just religion but in all facets of life, social, religious, political, economic.

But, that's not really what religions do, exist as personal belief systems that satiate individual spirituality, any more than modern party politics (Oh look! More religions!) exist to represent the people, let alone in the public arena of civil discourse, debate, and compromise.

I rather think you are looking at the wrong period of history for your parallels, by the way. The current hate and division is not all on Trump, the Trumpists, the Christians. It on the Americans. It's pervasive, not unique. Perhaps it would be more illuminating to look at the pre-Revolutionary and pre-Civil War eras for historical reference, deep divisions held with great vehemence laid bare.

I wonder when the successions will start.