>> Isn't faith by nature subjective? <<
Not according to the doctrine of catholicism. Personal and subjective experiences are needed to overcome the obstacle of doubt caused by original sin, but truth is universal, and the catholic Christian assertion is that the Christian God and the scriptures are the truth.
(The use of the word, "catholicism" is a little odd here. I do mean the name of a doctrine, and not the name of a denomination. However, the doctrine of catholicism rejects the possibility of schism, so from a Catholic-Church mindset, Protestantism is a rejection of catholicism, and not just Catholicism.)
>> Isn't prayer a belief in the super natural? <<
Yes, but the supernatural is objectively real.
Isn't a doctrine, subjective? Doesn't it require a belief?
In other words, truth by assertion.
...the supernatural is objectively real.
Just for the record, I believe both these.