The underlying principle of these new opinions is that, in order to more easily attract those who differ from her, the Church should shape her teachings more in accord with the spirit of the age and relax some of her ancient severity and make some concessions to new opinions. Many think that these concessions should be made not only in regard to ways of living, but even in regard to doctrines which belong to the deposit of the faith. They contend that it would be opportune, in order to gain those who differ from us, to omit certain points of her teaching which are of lesser importance, and to tone down the meaning which the Church has always attached to them. It does not need many words, beloved son, to prove the falsity of these ideas if the nature and origin of the doctrine which the Church proposes are recalled to mind. The [First] Vatican Council says concerning this point: “For the doctrine of faith which God has revealed has not been proposed, like a philosophical invention to be perfected by human ingenuity, but has been delivered as a divine deposit to the Spouse of Christ to be faithfully kept and infallibly declared. Hence that meaning of the sacred dogmas is perpetually to be retained which our Holy Mother, the Church, has once declared, nor is that meaning ever to be departed from under the pretense or pretext of a deeper comprehension of them.” (Constitutio de Fide Catholica, Chapter iv.)

We cannot consider as altogether blameless the silence which purposely leads to the omission or neglect of some of the principles of Christian doctrine, for all the principles come from the same Author and Master, “the Only Begotten Son, Who is in the bosom of the Father.” (John i, I8.) They are adapted to all times and all nations, as is clearly seen from the words of our Lord to His apostles: “Going, therefore, teach all nations; teaching them to observe all things whatsoever I have commanded you, and behold, I am with you all days, even to the end of the world.” (Matt. xxviii, 19.) Concerning this point the Vatican Council says: “All those things are to be believed with divine and catholic faith which are contained in the Word of God, written or handed down, and which the Church, either by a solemn judgment or by her ordinary and universal magisterium, proposes for belief as having been divinely revealed.” (Const. de fide, Chapter iii.)

Let it be far from anyone’s mind to suppress for any reason any doctrine that has been handed down. Such a policy would tend rather to separate Catholics from the Church than to bring in those who differ. There is nothing closer to our heart than to have those who are separated from the fold of Christ return to it, but in no other way than the way pointed out by Christ. – from Testem Benevolentiae Nostrae (1899)