Jahm bin Safwan
Jahm ibn Safwān (جهم بن صفوان) was an Islamic theologian who attached himself to Al-Harith ibn Surayj, a dissident in Khurasan towards the end of the Umayyad period, and who was put to death in 128/745-6 by Salim b. Ahwaz.
He was born in Kufah, but settled down in Khurasān in Tirmidh. His birthyear is unknown, but he probably was born in the first century (hijrah). He learned under al-Ja'd b. Dirham, a theologian from Harran in Syria. al-Ja'd b. Dirham was a teacher of the last Umayyad Caliph, Marwan II, and is described as a Dahrî and Zindîq. He was the first Muslim who spoke about the createdness of the Qur'ân, the rejection of Abraham's friendship to God and Moses' speaking to Him. From al-Ja'd Jahm b. Safwān inherited some doctrines and would become the founder of the Jahmiyyah (see: Jahmites).
Jahm was the first major propagator of the createdness of the Qur'ān. He believed that the Speech of God is created, since all attributes that are ascribed to God and which are shared by the creation are created too. There can be no sharing in name or attribute, according to Jahm, for that would necessitate assimilation (al-tashbîh). He therefore denied each and every attribute mentioned in the scriptures, for fear of anthropomorphism. The only attributes he accepted and described God with were two: creating and power. He believed that creating is the sole attribute that belongs properly to God and power too; all power witnessed among the creatures is metaphorically theirs, not literally. This last belief lead him to the doctrine of fatalism, called al-jabr (compulsion) for which they are called al-Mujbira. He based his theology upon a philosophical thinking he borrowed from non-Arabs  particularly, the early Greek philosophers.
Jahm's doctrines about God and His Attributes found a lot of adherence among the Mu'tazilah, Mutazilites, Ash'ari and Maturidi who were named Jahmites by their Salafi adversaries. The Mu'tazilah are known because of their belief that the Qur'ān is created, a tenet wherein they agreed with Jahm, and in a lesser degree Ash'ari and Maturidi agree with them. They would also were characterized by their sunni adversaries as deniers of God's Attributes in contradistinction of the affirmers from among the ahl al hadith, which would become Sunnites later on. 
Jahm b. Safwān was heavily criticized and declared an unbeliever by the ahl al hadith, who were increasingly becoming affiliated to the Umayyad, and later on, Abbassid authorities . Early on, many scholars of Hadith wrote refutations of Jahm bin Safwan's doctrines, particularly Ahmad ibn Hanbal, al-Bukhari, and al-Darimi. The latter also wrote a large refutation of a prominent Jahmite by the name of Bishr b. Ghiyāt al-Mārisî wherein he declared him a Kafir (an unbeliever).
Jahm left no writings, but many Muslim scholars of the past wrote about his doctrines and a few modern scholars wrote studies of him. For Internet resources about him and his doctrines:
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- Shorter Encyclopaedia of Islam p.83, Leiden 1974
- Abdus Subhan, al-Jahm bin Safwan and his philosophy p.221 in: Islamic Culture 1937, W. Montgomery Watt, Early Discussions about the Qur'ān p.28 in: The Muslim World 1950, al-Dahabi, Mizan al-I'tidal 1:185
- W. Madelung, The Origins on the Controversy concerning the Creation of the Qur'ān p.505 in: Orientalia hispanica sive studia F.M. Pareja octogenario dicata, Leiden 1974
- al-Bukhāri, Khalq Af'āl al-'Ibād no.4, Kuwait 1985
- al-Shahrastāni, Muslim sects and divisions p.72ff
- They wrote respectively: al-Radd 'alā al-Zanādiqah wa'l-Jahmiyyah, Khaql Af'āl al-'Ibād wa'l-Radd 'alā al-Jahmiyyah wa-Ashāb al-Ta'tîl and al-Radd 'alā'l-Jahmiyyah
- Refer to: Naqd 'Uthmān b. Sa'îd 'alā al-Mārisî al-Jahmî al-'Anîd fi Iftirā 'alā Allāh fî al-Tawhîd, Riyad 1999
- This makes the sources we have about Jahmiyyah tendentious and biased, as is the case with all heresiographies of the past. For modern studies see: Jamal al-Din al-Qasimi, Tarikh al-Jahmiyyah wa'l-Mu'tazilah, Yasir Qadhi, Maqalat al-Jahm b. Safwan wa Atharuah fi al-Firaq al-Islamiyya, and R.M. Frank, The neoplatonism of Ğahm ibn Safwân in: Le Museon 1965 p.395ff