Of course the medieval period covered a lot of time, and I'm sure there were always varying degrees of devotion, but how common would it have been to meet people who were just going through the motions and actually didn't care? What about those who questioned their belief in God? I'd imagine it would be hard for historians to know for sure since few people would publicly admit this?
You might be interested in some earlier discussions on this (and related) question(s). To begin, u/Kelpie-Cat has assembled a list of great earlier answers by u/sunagainstgold and others here. There are also this thread by u/Whoosier, this by u/mikedash, and this one by u/Aethelric
Also 'pinging' u/6th_Dimension who asked a similar question recently without getting an answer