To announce, therefore, to Catholic Christians anything besides that which they have received has never been lawful, is lawful nowhere, and never will be lawful; and to anathematize those who announce anything besides that which has been once received has always been necessary. This being the case, is there anyone of such audacity as to teach other than that which has already been taught in the Church, or anyone of such levity as to receive anything besides that which he has once received from the Church? St. Paul, the teacher of the Gentiles, cries aloud, and he cries out loud again and again, to all men, to all times, and to all places that, if anyone announces a new dogma, let him be anathematized!
St. Vincent of Lerins

The ancient doctrines must be confirmed, but novel and absurd inventions must be condemned and cast aside.

St. Cyril of Alexandria

Fly to the Catholic Church! Adhere to the only faith which continues to exist from the beginning, that faith which was preached by Paul and is upheld by the Chair of Peter.

St. Hippolytus of Rome

I cannot sufficiently be astonished that such is the insanity of some men, such the impiety of their blinded understanding, such, finally, their lust after error, that they will not be content with the rule of faith delivered once and for all from antiquity, but must daily seek after something new, and even newer still, and are always longing to add something to religion, or to change it, or to subtract from it!

St. Vincent of Lerins