Née d’un questionnement épistémologique sur la manière dont les concepts véhiculés par la recherche découpent le réel et sur la place de la subjectivité en sciences des religions, cette thèse analyse la vision de la mystique musulmane selon Louis Massignon (1883-1962). Elle met en lumière la posture herméneutique de ce chercheur qui, après avoir démontré l’origine qur’ānique du soufisme, fait de la figure d’al-Ḥallāj (m. 309/922), le paradigme de la sainteté en islām. L’analyse montre que sa vision de la réalité étudiée est tributaire de sa propre spiritualité : il perçoit la mystique authentique comme une voie d’ascèse, de purification par la souffrance. Au cœur de l’union mystique, le mystique devient le témoin de Dieu. A cette voie, il oppose celle d’Ibn ʿArabī (m. 638/1240) et perçoit l’influence du néoplatonisme comme une altération de la pureté ascétique primitive. La voie la plus pure est une mystique de l’annihilation (fanā’) au sein de laquelle l’être humain serait indigne d’endosser les attributs divins et de connaître l’état de subsistance (baqā’). Sa quête, mue par des questionnements existentiels, illustre la difficile conciliation entre la quête du vrai et la quête de la Vérité. Cette étude montre combien la subjectivité du ou de la chercheur.e sert la recherche et l’entrave à la fois. Elle suggère, afin de construire les conditions du comprendre qu’il importe de prendre conscience de la particularité de sa posture herméneutique, d’énoncer son intention, d’interroger ses catégories conceptuelles, de maintenir une distance critique à son sujet, de réfléchir sur sa pratique, afin que la subjectivité ne déforme pas le réel, mais l’éclaire et le révèle. / Born from epistemological questions about the way in which the concepts conveyed by research cut out the real and about the place of subjectivity in the academic study of religion, this thesis analyzes Louis Massignon’s (1883-1962) vision of Muslim mysticism and provides the following key results: In a context in which mysticism is attracting increasing interest and in which the study of religion and of Islam more specifically are becoming institutionalized, this orientalist thinker, contemporary of both French and British colonial expansion, experimented with various tensions between scholarly and political logics, between academism and civilizing mission. Biographical sources make it possible to trace an itinerary that originated in Paris, continued in Cairo, and led him to Baghdad, the city where Ḥusayn b. Manṣūr al-Ḥallāj, to whom Massignon dedicated his doctoral dissertation, had died in 309/922. Interesting himself particularly in the lexical dimension of Sufism, he demonstrated, by means of an interiorist method of reading texts, its Qur’anic origin and its fundamentally Islamic character. These contextual and biographical analyses shed light on the specificity of Massignon’s hermeneutic posture vis-à-vis Muslim mysticism. It is as an interpreter inspired by a Christian vision of holiness that he approaches the figure of al-Ḥallāj and makes the latter the paradigm of holiness in Islām. This research brings to light how this Christian scholar’s spirituality influenced his vision of his field of study. The ḥallājian mystic - the purest in his eyes - is conceived as on a path of asceticism, of purification through suffering. At the heart of the transforming and personalizing union, this mystic becomes the witness of God. The mystic can only join with God in atonement, love, and sacrifice. Massignon’s vision thus opposes that of Ibn ʿArabī (d. 638/1240), which he reproaches for suppressing the radicality of transcendence. The Islām of theophanies is, in his eyes, pantheism; he refuses all mediation and perceives the influence of Neoplatonism as an alteration of primitive ascetic purity. If authentic mysticism is, in according to him, a mystique of aridity, of annihilation (fanā’) , it is because in his eyes, the absolute smallness of the human being is matched only by divine omnipotence: the inconsistency of the human being makes them unworthy to endorse the divine attributes and to know the state of subsistence (baqā’ ). This study analyzes, finally, how Massignon’s existential questions affect the way he looks at the reality he is studying. His effort illustrates the difficult reconciliation between the (scientific) quest for the true and the (metaphysical) quest for the Truth. Through this case study, this research demonstrates how the subjectivity of the researcher supports research and hinders it at the same time. The study ultimately establishes why it is important to become aware of the peculiarity of one’s hermeneutical situation, to state one’s intention, to question one’s conceptual categories, to maintain a critical distance from one’s work, and to wonder about one’s practice in a reflexive way: these precautions help build the condition of a more just understanding, so that subjectivity no longer deforms reality, but illuminates and reveals it.