Criticism of Islam is an inseparable part of the general debate on Islam. It became particularly relevant in the context of the emerging of religious fundamentalism and the use of violence in the name of Islam. This article intends to provide a brief overview of religious-critical ideas in Islam, to elaborate on an internal Islamic-based religion criticism and to reflect on the possibility of a secular criticism in Islam in line with modern Western religious criticism. The concluding reflections deal with the reasons for the need of religious criticism in Islam.