I have some reservations about the epistemology of the Thomist/Aristotelian language in which the doctrine on transubstantation is expressed. It seems to imply a kind of deductive method which is impossible to correct when it fails to correspond to observable reality.
Is it possible to be a Catholic, and to say “I believe the host really is the Body of Christ in ultimate reality” because that reality is created by the generative Word of God at the moment that He instituted the sacrament with the words “this is my body”, though I perceive the host to be bread. This would follow a more naturalistic epistemology, where the “accidents” are actually perceptual qualities in me rather than objectively possessed by the “substance”, which is the Body of Christ.
I’m still saying “The host really isn’t bread, it really is the body of Christ”. I’m just expressing it in a way that isn’t so problematic to an empiricist (i.e. non-Aristotelian) philosophical position.
I guess what the question comes down to is, do you have to be a Thomist to be a Catholic?