Which doctrine do I blindly follow?
What doctrine do you not follow if it is defined ex cathedra? no matter how preposterous or absurd or downright contrary to holy writ.
The doctrine of transubstantiation
There is a little trick called development, which supposes that the mass is merely a development of the last supper. And they are perfectly able to say "based upon scripture" and they have the people bowing down to worship the bread tut tut
Did Jesus say "this is My body"? yes He did...then He blessed and break it and they ate...see? the body broken is no more body.
The apostolic tradition is to bless and brake and eat.
...see that you call no man on earth father or teacher