Or merely that it was in some sense easier for them to do so, even if that wasn't actually demonstrated by their actions?
The latter. The former is an empirical claim I'm not yet sure how we could properly resolve. But there are reasons to think it may have been true.
After all the King is a Christian and so am I. It is merely that God has placed a greater burden of responsibility on him and one of toil on me. We all have our own cross to carry.
I'd say you're looking at the history of feudal hierarchy through rose-tinted glasses. People who are high in the instrumental hierarchy of decisions (like absolute rulers) also tend to gain a similarily high place in all other kinds of hierarchies ("moral", etc) due to halo effect and such. The fact that social or at least moral egalitarianism logically follows from Christian ideals doesn't mean that self-identified Christians will bother to apply it to their view of the tribe.
Remember, the English word 'villain' originally meant 'peasant'/'serf'. It sounds like a safe assumption to me that the peasants were treated as subhuman creatures by most people above them in station.
If it's worth saying, but not worth its own post, even in Discussion, it goes here.