I am aware that identifying belief in documentary papyri didn't make it onto anyone's top-ten list of anything but it can be rather interesting. But then we get to a case such as this where it simply becomes a tad confusing:
(Click to Enlarge)
Here we have a papyri letter with many allusions we would simply interpret as Christian. We have the Father God, we have a Paraclete Spirit, we have a Paschal festival...but is it Christian?
I would say the answer will surprise you but I don't think anyone is yet to produce a real solid answer.