In fact, religious ideas (at least in Europe) were often in opposition to the ruling elite (and still are) and even inspired rebellion: https://en.wikipedia.org/wiki/John_Ball_(priest)

There is a reason scriptures were kept away from the oppressed, or only made available to them in a heavily censored form (e.g. the Slaves Bible).

That's a very good point. Some of what's called "science" today, in popular media and coming from governments, is religion. "We know all, do not question us." It's the common problem of headlines along the lines of "scientists say" or "The Science says", which should always be a red flag - but the majority of people believe it.

A little more complicated than that.

In the past, the elites said "don't read the religious texts, WE will tell you what's in them."