I want to know the answer to the following question:
What was the name of the ecumenical council that made the decision ?
All the background I'm provided with is that "The Council of Trent decreed: "If anyone shall say that a man once justified can sin no more, nor lose grace, and that therefore he who falls and sins was never truly justified; or, on the contrary, that throughout his whole life he can avoid all sins even venial sins, except by a special privilege of God, as the Church holds in regard to the Blessed Virgin: let him be anathema."". Is that enough to answer the question?
Answer: yes