Catholic doctrine and dogma can be quite specific (such as the nature of Jesus) and because the masses were conducted in Latin, a foreign language to most peasants, I would imagine that their knowledge of Christianity would be limited. But this seems to be contradicted by the demonstrations of intense religiosity on the part of many, such as pilgrimages . So, how much did the average peasant know about Christianity in the medieval period?
There is always more to say, but versions of this question have cropped up here before and you might find it helpful to review some of those earlier threads while waiting for fresh responses to your query:
How versed in Christian dogma was the average medieval peasant? with u/Whoosier
The same flair (who's a specialist in popular religion and has taught college level courses in medieval history for decades) also hosted a helpful AMA here a while back:
I am a peasant in medieval France - how well do I know my religion? with u/sunagainstgold
I'm a peasant living in 1300s England. How hard would it be to get a copy of the Quran. Is it even possible? Would I even know what the Quran is? What would happen if authorities caught me with it? with u/sunagainstgold