A rigid monotheism appeared to Plotinus a miserable conception.
Monotheism henceforth was to be the belief not of philosophers only but even of the ignorant, and in Jesus Christ the union of the divine and the human was effected.
The goal towards which these tendencies verged was monotheism; and though this goal was only once, and then quite ephemerally, reached, still the monotheistic idea was at most periods, so to speak, in the air.
Sufism (q.v.) appears in the 9th century among the Mahommedans of Persia as a kind of reaction against the rigid monotheism and formalism of Islam.
This explanation was the more urgent because under the influence of Jewish monotheism the rule of God was accepted as an undoubted presupposition, so that the death of Jesus must be in accordance with his will.