He settled in Baghdad, until he was invited to Rey in 367 AH/978 CE by its governor, Sahib ibn Abbad, a staunch supporter of the Mu'tazila theological movement .
On the death of ibn 'Abbad in 995 CE, Abd al-Jabbar was deposed and arrested by the Buyid Amir, Fakhr al-Dawla, because of a slighting remark made by him about his deceased benefactor.
Qadi ʿAbd al-Jabbar's magnum opus, the Kitab al-mughni fi abwab al-tawhid wa l-ʿadl (Book of the plenitude on the topics concerning unity and justice), often shortened to al-Mughni, is a comprehensive twenty volume "summa" of Mu'tazilite theology of the same magnitude as St. Thomas Aquinas's Summa Theologica and Summa Contra Gentiles.
[1] It presented Mu'tazili thought under the two headings of God's oneness (tawhid) and his justice (adl).
[6] Abd Al-Jabbar produced an anti-Christian polemic text Tathbit Dala’il Nubuwwat Sayyidina Muhammad صلى الله عليه وسلم, (‘The Establishment of Proofs for the Prophethood of Our Master Muhammad صلى الله عليه وسلم’).