Two alarming examples of sectarian violence have occurred this week that raise new concerns about the spread of religious-fuelled violence in the Middle East.
In the first, four Egyptian Shiites were killed in a mob attack on their place of worship in Giza. A group of Salafists attacked the mosque, killed the men and then desecrated the bodies. The attackers said the victims were spreading their religious teachings in Egypt.
In the second incident, Sunni Salafists in Sidon, Lebanon, killed at least 30 soldiers and injured more than a hundred in the bloodiest outbreak in the country for years. The Lebanese Salafists, led by the hardline Sunni cleric Ahmed Assir, were angered by what they believe is unfair treatment from the army, accusing the forces of indiscriminately targeting Sunnis while failing to respond to Hizbollah's provocations.
Those clashes specifically threaten to turn Lebanon's Sunni population into victims once again, as the hard-line tendencies of a few come to be seen as speaking for many.
These incidents are particularly alarming as authorities in the two countries have failed to contain sectarian rhetoric in recent months. In both Egypt and Lebanon jihad was declared by prominent Sunni clerics against Shia. Especially in Lebanon, vows like these will raise serious concerns for a nation that has suffered from sectarian war.
Syria, of course, is the crisis that is fuelling much of this violence. Hizbollah's entry into that conflict, over the objections of even Hamas, were always going to sow discord regionally and across the border. Iran's support of the militants, and Gulf and western states' support of opposition fighters, is only adding to the fires.
Most worrying of all is how little the region has learnt from past periods of sectarian bloodletting. Sectarian tensions ripped Iraq to its ideological core in early 2006; that country has yet to recover. The civil war in Lebanon that ended in 1990 still divides the nation.
And yet, rather than tone down rhetoric and actively seek to avoid the pitfalls of regional wars, some clerics and political leaders are looking to gain by stoking populist hatred.
Rather than seeing these events as isolated incidents contained within borders, political and religious leaders must see this latest surge of violence for what it truly is: the makings of a sectarian catastrophe. The clashes in Giza and Sidon are tragic reminders that everyone loses when men and women of different beliefs attack those whose only crime is to disagree.