He then moved to an apartment on Rue Las Cases in 7th arrondissement of Paris to focus exclusively on philosophical research and intellectual apostolate.

[4] In 1906, his works Essais de philosophie religieuse and Le réalisme chrétien et l'idéalisme grec were censured.

During the First World War, Laberthonnière was asked by Henri-Louis Chapon, Bishop of Nice to write a doctrinal letter condemning Pan-Germanism.

He served as chaplain to blind soldiers at the Hôpital des Quinze-Vingts, where he met his friend the Protestant pastor Marc Boegner.

He utilized the "method of immanence" treated of skeptically by Pope Pius X in Pascendi Dominici gregis and emphasized the interior experience of Christianity against the empirical claims of apologetics.

[5] Laberthonnière was loosely associated with Le Sillon though he had a poor relationship with Marc Sangnier and was a public opponent of Charles Maurras and Action française.