I have a question revolving around the beliefs of those under the Catholic moniker. More specifically, I have a question regarding the role of the Church and its authority. To illustrate this question more indepth (and to give you an idea about the inspiration for my question), I refer to the following sentence written by a blogger out in cyberspace:

“The Protestant reformulation of justification as forensic declaration, with the accompanying sola fide, represents a significant departure from the Church’s understanding of justification.”

Now, of course this is out of context to what the author is discussing, but for the purposes of this discussion, the authors context is moot. What is relevent is the fact that he states that something, in this case justification doctrine, “represents a significant departure from the Church’s understanding.”

The Church’s understanding. I assume that he means the Catholic Church (as a reference to the church body would leave the implied authoritative stance out of the picture). So, in light of this, how does the following logic play out in the rest of Christendom?

If the Catholic Church is God’s authority over the body of Christians (the ability to depart, in this sense, infers that the Catholic Church is the definitive authority) How then can I, as a generic Christian, remain under God’s authority without submitting to the Catholic Church and am I damned if I conduct my spiritual life outside of Catholic authority?

In addition, what basis does the blogger have in assuming that everyone believes in The Church’s authority enough to use it as a rebuttal to a debate with non-Catholics?