Over the past two years, Muhammed Khurshid Khan has traveled to Sikh shrines in Pakistan and India, volunteering to polish shoes, clean bathrooms, cook meals and do other chores. Such service is known as "seva" — selfless service — in Sikhism, and it holds a special place in the faith.

Attacks against Sikhs, Christians and Hindus have spiked in Pakistan in recent years as the Taliban and their allies gained strength. Atrocities ...