Vatican II Responsible
"...We quote from the Canadian Catholic Register, January 10, 1987, quoting NC News Service, “The unity shown by world religious leaders who prayed for peace in Assisi, Italy, last October (1986) was “visible illustration” of the Second Vatican Council’s call for ecumenism and interreligious dialogue, Pope John Paul II said.” This speech was laced with quotations from the documents of Vatican II, which he said showed how “such a great event sprang from the teaching of the council.” Here we have the source of all this – Vatican II – and there can be no question of “misrepresentation” since the Pope himself has interpreted it. Our Lord did not call for “ecumenism and interreligious dialogue.” Our Lord said: “Go ye therefore and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost.”..."
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"Now I beseech you, brethren, to mark them who make dissensions and offences contrary to the doctrine which you have learned, and avoid them. For they that are such, serve not Christ our Lord, but their own belly; and by pleasing speeches and good words, seduce the hearts of the innocent." Romans 16: 17-18
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"For the holy Spirit was promised to the successors of Peter not so that they might, by his revelation, make known some new doctrine, but that, by his assistance, they might religiously guard and faithfully expound the revelation or deposit of faith transmitted by the apostles." (Decrees of the First Vatican Council Chapter 4. On the infallible teaching authority of the Roman pontiff)
Ecumenism = new doctrine