Agamben on secularization

"In this sense, secularization operates in the conceptual system of modernity as a signature that refers back to theology. Just as, according to canon law, the secularized priest had to wear a sign of the religious order he had once belonged to, so does the secularized concept exhibit like a signature its past belonging to the theological sphere. The way in which the reference operated by the theological signaure is understood is decisive at every turn. Thus, secularization can also be understood [...] as a specific performance of Christian faith that, for the first time, opens the world to man in its worldliness and historicity. The theological signature operates here as a sort of trompe l'oeil in which the very secularization of the world becomes the mark that identifies it as belonging to a divine oikonomia."

Giorgio Agamben, The Kingdom and the Glory: For a Theological Genealogy of Economy and Government (Stanford University Press, 2011), 4