Final answer:
The religious movement that pursued spiritual unity with God and rejected the worldliness of the Abbasid Caliphate was Sufism.
Step-by-step explanation:
Option A
The religious movement that rejected the worldliness of the Abbasid Caliphate and instead pursued spiritual union with God is Sufism. Sufism is a mystical form of Islam that involves personal worship and the search for spiritual purity. Unlike the political ambitions of the Sunni or Shia movements, Sufism focused on renouncing luxury and worldliness to achieve a mystical union with God, often through asceticism and meditation.
Sufis aimed for heartfelt worship rather than outward religious performance, and they were critical of rationalizing religion and the blending of Greek philosophy into Islamic theology.