For example, I read Tom Sawyer and Huckleberry Finn (the pre-sanitized version) by Mark Twain and it was genius. Everybody knows what a literary giant Samuel Clemens was and his scathing satires of culture and institutions. What I didn't know was that he was a raving anti-Catholic.
For fun, I recently listened to a recording of A Connecticut Yankee In King Arthur's Court. I had two general observations.
One, that the book was actually too long for the subject matter it treated (it got wearisome to listen to the hundreds of permutations of a 18th century New Englander's crusade against Medieval England's ideas - a few would have sufficed.)
The second, was that Clemens never missed an opportunity to impugn the Catholic Church, faith, the concept of dogma, he feared the Church's power, patriarchy and so on. His is a truly relativistic view.
I had started a teacher-factory and a lot of Sunday-schools the first thing; as a result, I now had an admirable system of graded schools in full blast in those places, and also a complete variety of Protestant congregations all in a prosperous and growing condition. Everybody could be any kind of a Christian he wanted to; there was perfect freedom in that matter. But I confined public religious teaching to the churches and the Sunday-schools, permitting nothing of it in my other educational buildings.
I could have given my own sect the preference and made everybody a Presbyterian without any trouble, but that would have been to affront a law of human nature: spiritual wants and instincts are as various in the human family as are physical appetites, complexions, and features, and a man is only at his best, morally, when he is equipped with the religious garment whose color and shape and size most nicely accommodate themselves to the spiritual complexion, angularities, and stature of the individual who wears it;
and, besides, I was afraid of a united Church; it makes a mighty power, the mightiest conceivable, and then when it by and by gets into selfish hands, as it is always bound to do, it means death to human liberty and paralysis to human thought.
Not a new thought perhaps, but newly disappointing.