"[1] During the second meeting, van Santen refused to sign the Formulary of Alexander VII that was presented by Capaccini, thus condemning five propositions purportedly contained in the Augustinus and affirming the authority of the pope.
Moss, van Santen replied: "I know that the Five Propositions, as condemned, are not contained in that book; how can I, then, as an honest man and a Christian, sign a declaration which denies the fact?
Moss concludes: "If [van Santen] had accepted the Formulary, and his two suffragans with him, their names would have been acclaimed throughout the Roman Catholic world…as the men who by their submission had healed the 'Jansenist schism'; …And yet he would not, for any advantage in this world or the next, declare that to be true which he was quite sure was false.
When Pius IX issued the papal bull Ineffabilis Deus on 8 December 1854, proclaiming the dogma of the Immaculate Conception of Mary, van Santen responded with formal protest.
On 14 September 1856 he and his two suffragans, Bishop Henricus Johannes van Buul of Haarlem and Hermannus Heykamp of Deventer, penned a letter to Pius IX, protesting the new dogma on three grounds: that it was contrary to scripture and tradition, that the bishops of the Church had never been consulted about it, and that it was a novel, false doctrine.