A monoploy on the fullness of Truth, yes.
That doesn't mean that everything that other denominations teach is error. Only that there is error mixed in with the truth in other denominations.
If you want truth you can find it elsewhere. But if you want the truth, the whole truth and nothing but the truth, then you must cross the Tiber.
SD
Is it any wonder that many children were not believed when they reported abuse by priests? It is all part of a "we are always right" state of mind IMO.