Not only that, roscoe, but once you subjectivize everything, the absurd conclusion follows that the Catholic Church is an impediment to salvation rather than a "help".
You might have a Protestant who just goes to church every few weeks, when he feels like it. Since he's not aware of any obligation to go to church, he commits no sin. But a Catholic misses Mass once and he's in a state of mortal sin. Protestants can divorce and remarry 20 times and not be in sin, but a Catholic enters a perpetual state of sin in doing it once. Lest the BoDers object, neither of these examples has to do with following the natural law.