The Amman Message began as a statement issued in Jordan in November 2004 on what Islam is and what actions represent it. What gave it legal weight came afterwards. Over the following months questions were put to senior authorities across the Muslim world, and their answers were assembled into three points which an international conference in Amman ratified in July 2005.
The first point lists the schools of law whose adherents are Muslims: the Hanafi, Maliki, Shafii and Hanbali schools; the Jafari and Zaydi schools; the Ibadi school; and the Zahiri school. It adds that whoever follows Ashari doctrine, or practises real Sufism, or follows true Salafi thought, is a Muslim. The list is the point. It is a mutual recognition among traditions that have spent centuries disputing each other's standing.
The second point follows from the first. It is not possible to declare as apostates any group of Muslims who believes in God, in the Prophet, in the pillars of the faith, and who respects the pillars of Islam and does not deny any necessarily known tenet of religion. Takfir between the recognised schools is closed.
The third point concerns competence. It states the subjective and objective preconditions for issuing a fatwa and forbids any person to issue one without the qualifications the schools themselves define, and without following their methodology. A ruling from an unqualified source is, in the words of the text, not a fatwa.