Sectarian tensions in Pakistan have gone from bad to worse ever since riots broke out in Rawalpindi a month ago. On Sunday, a Shia cleric was murdered in Lahore. The killing was seen as a response to the assassination of a Sunni leader of a religious party known for its anti-Shia rhetoric. And on Wednesday, three people were killed as a suicide bomber tried to break into a Shia mosque in Rawalpindi.The Pakistani government has called for calm, and has heightened security around Shia mosques, churches and temples, but the attacks continue. The sectarian tensions in Pakistan mimic the increasingly lethal tensions in Lebanon, Iraq and Syria. But Pakistan’s sectarian troubles are more a product of a radicalized society, and less a backlash to the geopolitical machinations of the region. Thousands of seminaries all over the country, funded by Saudi petrodollars, churn out Salafist radicals who see Shias as heretics. Organizations that fall under the Pakistani Taliban, like Lashkar-i-Jhangvi and Sipah-i-Sahaba, have targeted Shias in suicide bombings and targeted killings, particularly in urban centers that have large Shia populations. High-casualty attacks like the bombings in predominantly Shia neighborhoods in Karachi and Quetta have underlined what has been a sustained campaign to terrorize the community.In response, loud, equally radical Shia groups have also emerged that have been carrying out revenge attacks on prominent Sunni leaders, causing a spiral that has lately threatened to veer out of control. Iraq seems to be in danger of falling back into a bloody, sectarian civil war, and Syria is already in one. To say that nuclear-armed Pakistan going down a similar path would be a very bad thing would be an understatement.