Complex sentence: In this context, Voegelin put forward his "gnosticism thesis": criticizing modernity by identifying an "immanentist eschatology" as the "gnostic nature" of modernity.
Split into simpler sentences: In this context, Voegelin put forward his "gnosticism thesis". Voegelin thus criticized modernity by identifying an "immanentist eschatology" as the "gnostic nature" of modernity.