Despite Qurʾān 2:256 and its prevalent intepretation, Muslim books of tradition and jurisprudence include extensive chapters on groups of people who should be forced to accept Islam. We have already surveyed the views of Muslim jurists concerning idolaters of various ethnic affiliations, as well as women, children and prisoners of war in certain circumstances. Another group against whom religious coercion is to be applied are the apostates (murtaddūn), people who had been Muslims but renounced their faith.

In order to become a Muslim, one has to pronounce the twofold declaration of faith (shahāda), affirming the oneness of Allah and the prophethood of Muḥammad. Though the conditions of conversion are not the same for members of all religions and the issue is more complex than it seems to be in the general expositions of Islam, the double declaration of faith is, in the overwhelming majority of cases, an indispensable condition for joining the Muslim fold. The simplest manner of leaving Islam is, naturally enough, an explicit conversion to another religion. In addition to this, retraction of the two declarations of faith, or of one of them, would also signify the believer's decision to fall away from the faith. And, indeed, the jurists maintain that denial of the shahāda is the foremost indication of apostasy. It is, however, not the only one.