Pakistan, Nov. 4 -- In May 2016, when an American drone strike killed Mullah Akhtar Mansour, the Afghan Taliban faced a succession problem. They settled on Hibatullah Akhundzada, a cleric better known for his command of religious law than for leading men into battle. The choice was deliberate. A movement fractured by war needed someone whose authority could be presented as a matter of doctrine, beyond the rivalries of field commanders. A decade later, the doctrine associated with that same leader poses a rather inconvenient question for the Tehreek-i-Taliban Pakistan.

Hibatullah served as a religious judge during the Taliban's first period in power and later became an influential figure in its judicial hierarchy. After assuming leadershi...