The wiki post isn’t accurate
TESTEM BENEVOLENTIAE NOSTRAE
Concerning New Opinions, Virtue, Nature And Grace, With Regard To Americanism
Pope Leo XIII
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 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,
here is a link to the whole document
In other words, the heresy is don’t preach it if it could irritate someone. There is more to this heresy but that is one of the main points.This heresy is alive and well in the USA. I think it is more popular than Modernism (its sister heresy).
For example I went to mass for All Souls day. The sermon spoke about our departed love ones in heaven. At the end of the mass we prayed for the faithful departed.
I asked the priest “Why did we pray FOR the faithful departed at the end of mass?”
He said, “Because we miss them.”
I said “Not because they may be in Purgatory? Isn’t that still a Dogma Father?”
His face dropped and he stutter out “yes, oh, yes that’s still a teaching.”
I said “Well I wouldn’t have known it by your sermon, father. That’s why the feast of All Souls day was started- to pray and understand the dogma of Purgatory! Wasn’t it?”
When was the last time you heard a sermon on hell?
On the Rosary? on Mortal and Venial Sin? etc…