In 1902, he started to pay attention to Adolf von Harnack's "Das Wesen des Christentum". Harnack believed that the essence of Christianity was the relationship between individual and God, making an organized church a largely unnecessary creation. Loisy disagreed with the idea that the organized church was unnecessary, but the nature of his disagreement brought him controversy. From 1901 to 1903 he published several works that would be condemned by the church. These include "La Religion d'Israël", "Études évangéliques", "L'Évangile et L'Église", "Autour d'un petit livre", and "Le quatrième Évangile". His 1908 "Les Évangiles Synoptiques" would cause his excommunication. In his works he argued against Harnack, trying to show that it was necessary and inevitable for the Catholic Church to form as it did. In doing so, Loisy implicitly accepted the consistent eschatology of Johannes Weiss: Jesus thought the coming of the Kingdom was imminent, so there was no point in founding a Church. Only after his death and resurrection his original proclamation of the Kingdom was transformed in this sense by his disciples, and legitimately so, as Loisy pointed out against Harnack's conception of Christianity: 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. Although "L'Évangile et L'Église" in particular was condemned by Cardinal Richard, Pope Leo consistently refused to interfere directly. It was his successor, Pope Pius X who would later condemn these works.