Pakistan's Sullied Shrines

Karachi's mosques offer an oasis of shade and tranquility in this sweltering city. But fewer Karachiites are responding to the muezzin's call to prayer these days. The city is experiencing one of its periodic spasms of vengeful warfare between extremist members of Islam's Sunni and Shi'a religious sects. Mosques are a favored target.

The violence erupted early last month when 32-year-old Sunni police trainee constable Akbar Niazi wired himself with explosives and blew up the Haideri mosque, killing himself and more than 24 Shi'ites. Next to die was radical Sunni Muslim cleric Mufti Nizamuddin Shamzai, 51, who was...