[Astromancer]

The USA is often described as having a "Civic Religion." But through most of our History, at least up to the 1950's we resisted being called a religious nation. Jefferson and Hamilton fought over many things, neither man ever allowed that the USA could be seen as a Christian Nation. In fact durring Jefferson's nogotiations with the Barbary Pirates he stressed that America was in no way a Christian nation, and there are no reports of anyone in Congress objecting in the least.

Lincoln was aproached by more than one deligation of ministers brutally trying to pressure him into declaring the USA a Christian nation as the CSA had declared itself a Christian nation. The Blackmail was intense, but Lincoln ignored it as did the Congress.

Although both Wilson and FDR were devout Christians, both men rejected all attempts to declare America a Christian Nation. There were no objections from Congress to their resistance.

Durring this period the USA had a very high church attendence, often higher than in nations were Church attendence was compulsorary. A Nation can be officially agnostic and run in a secular manner while having a deeply religious populace. The 3I would make a similar choice.

Or they could be like the Ancient Romans who said "The people find all religions equally true, the phillosophers find all religions equally false, and the politicians find all religions equally useful."

Either way, the people at the top would lead secular lives. If religious, they'd keep it private.