He took his theological degree in March 1890, by the oral defense of forty Latin scholastic theses and by a French dissertation, Histoire du canon de l'ancien testament, published as his first book in that year.
[8] In November 1893, Loisy published the last lecture of his course, in which he summed up his position on Biblical criticism in five propositions: the Pentateuch was not the work of Moses, the first five chapters of Genesis were not literal history, the New Testament and the Old Testament did not possess equal historical value, there was a development in scriptural doctrine, and Biblical writings were subject to the same limitations as those by other authors of the ancient world.
In his works he argued against the views of Adolf von Harnack, the German Lutheran theologian, who was trying to show that it was necessary and inevitable for the Catholic Church to form as it did.
Only after his death and resurrection was his original proclamation of the Kingdom transformed into this sense by his disciples, and legitimately so, as Loisy pointed out against Harnack's conception of Christianity: It is certain, for instance, that Jesus did not systematize beforehand the constitution of the Church as that of a government established on earth and destined to endure for a long series of centuries.
But a conception far more foreign still to His thoughts and to His authentic teaching is that of an invisible society formed for ever of those who have in their hearts faith in the goodness of God [Harnack].
Such a principle is contrary to the law of life, which is movement and a continual effort of adaptation to conditions always new and perpetually changing.
[9] The second part of the quotation echoes Cardinal Newman's theory on the development of Christian doctrine which Loisy had studied in his time at Neuilly.
Another controversial thesis of Loisy, developed in La Religion d'Israël, is the distinction between a pre-Moses period, when the Hebrews worshipped the god El, also known by the plural of this name, Elohim, and a later stage, when Yahweh gradually became the only deity of the Jews.
Urged by the Parisian Archbishop Cardinal Richard, Pius X transferred the scrutiny of Loisy's books, started under Leo XIII in 1901 under the Congregation of the Index, to the Holy Office.
By 23 December 1903, the Congregation censured Loisy's main exegetical works: Religion d'Israël, L'Évangile et l'Église, Études évangéliques, Autour d'un petit livre and Le Quatrième Évangile.
[14] Due to ongoing internal resistance, especially from the Master of the Sacred Palace, the papal theologian Alberto Lepidi, this syllabus was published only in July 1907 as the decree Lamentabili sane exitu[15] (or "A Lamentable Departure Indeed"); it condemned sixty-five propositions from the field of biblical interpretation and the history of dogma.
This was soon followed by the encyclical Pascendi dominici gregis ("Feeding the Lord's Flock"), which characterized modernism as the "synthesis of all heresies".
If I am anything in religion, it is more pantheist-positivist-humanitarian than Christian.His Catholic critics commented that his religious system envisioned a great society which he believed to be the historically developed Church.
Yet the great bulk of the sayings is acknowledged as substantially authentic; if the historicity of certain words and acts is here denied with unusual assurance, that of other sayings and deeds is established with stronger proofs; and the redemptive conception of the Passion and the sacramental interpretation of the Last Supper are found to spring up promptly and legitimately from Christ's work and words.
On 14 February 1908 Léon-Adolphe Amette, archbishop of Paris, prohibited his diocesans to read or defend the two books, which "attack and deny several fundamental dogmas of Christianity," under pain of excommunication.