The prudential judgments of councils (“This is how we are going to do things–for now.”) represent snapshots of the Church’s evolving thought. Lateran IV shows how Catholics of the time thought about religious liberty: they didn’t buy it and couldn’t see how to square it with their knowledge at the time. But then, neither did anybody else.
But at the same time, their own tradition insisted that freedom was a good thing and that conscience should not be compelled (“We must obey God rather than men.”) So they did what Catholics do and made their best guess about how to proceed (rather like Catholics today who know from their tradition that war is a manifestation of sin, but who still say, “Going to war seems like our best option, for now.”)
The move from “error has no rights” to “Persons in error do have rights” is obvious to us because we are on the other side of the historical divide (though there are lots of person in error–advocates of incest and pedophilia, neo-nazis, white supremacists, Muslims, etc.–that many postmoderns are ready to lock up for their opinions alone, whether or not they act on them.)For much of postmodernity, it’s not really that we are more tolerant than our ancestors, it’s just that we no longer care about the ideas they cared about intensely and we now care about different ideas intensely. If we *really* believed that false ideas spelled the difference between eternal salvation and eternal damnation (as we now believe some ideas spell the difference between a peaceful morning at work and a billion tons of concrete and steel pulverizing the lives out of 3000 people in the Twin Towers) there are millions ready at this moment to deny the most elementary civil rights to anybody they so much as suspect might be a threat and torture them to death to stop it.
The main difference between us an our Catholic ancestors is that they feared the second death and we are terrified of the first death.
The Church lives in that space of tension between “love your enemies” and “the average Catholic is average and would, under the wrong circumstances, deny Christ if he thought he could save his skin.” That we have figured out that persons in error have rights at all is a miracle of grace. We are extraordinarily slow on the uptake. Concupiscence sucks.