If the Church, the faithful guardian of truth, lose the truth, by whom shall the truth be found?
—St. Francis de Sales
Exactly. And this is why Protestantism destroys any hope whatsoever of ever discovering revealed truth: because the Protestant claims that the Church—any and every church—can err, does err, and has erred. The instant that we say that the truth was not preserved in the Church through all ages, we lose any and all access to revealed truth and are left with various competing opinions.