Jansenism (Jansenisme) is a polemical term introduced by critics to label those sympathetic to the theological views of the Louvain theologian and later bishop of Ypres, Cornelius Jansenius (1585–1638), author of the Augustinus (posthumously published in 1640) (see Orcibal 1953). In the Augustinus, Jansenius calls for a return to the emphasis in Augustine on the importance of the workings of grace in the salvation of the elect, against the heretical view of Pelagius that we can obtain salvation through the use of our free will alone. The papal bull Cum occasione (1653) condemns as heretical or temerarious the following five propositions that anti-Jansenist theologians in the Sorbonne claimed to find in Jansenius's text:

1. 1.Some of God's commandments are impossible for the just despite their desire and their effort to obey them, given the powers that the just now possess and also the lack of grace that makes it possible to obey the commandments.

2. 2.In the state of fallen nature, no one ever can resist interior grace.

3. 3.To merit or demerit in the state of fallen nature, it is not required that man be free from the necessity of willing and acting; it is sufficient for him to be free from constraint.

4. 4.The Semi-Pelagians admitted the necessity of interior prevenient grace for all good works, even for the beginning of faith; but they were heretical in claiming that this grace is such that the human will may either resist or obey it.

5. 5.To say that Jesus Christ died and shed his blood for all men, without a single exception, is to speak as a Semi-Pelagian.

A later bull, Ad sacram (1656), closes a loophole created by the fact that Cum occasione did not mention the Augustinus explicitly, in claiming that the five propositions are to be found in Jansenius's text in their condemned sense. Thus did Jansenism become a formally defined heresy within the Catholic Church.