While over 90 percent of terrorism related deaths worldwide are caused by Islamic terrorists (who mainly kill other Moslems) most of the non-Islamic terrorist deaths are caused by the few remaining leftist (usually communist) rebel groups. In fact, during 2015 of the top four most deadly terror groups worldwide, one was a radical communist movement. These are the Maoists (or Naxalites) of India. In 2015 they were responsible for 176 deaths. The top three killers were ISIL (Islamic State in Iraq and the Levant) with 6,100 dead followed by Boko Haram (in Nigeria) with 5,500 dead and the Taliban (in Afghanistan and Pakistan) with 4,500 dead. The Indian Maoists were a distant fourth. During the last few years the Maoists have edged out Islamic terrorists as the leading cause of terrorism related deaths throughout India.
There aren’t many active communist rebel groups left and the main ones like the NPA (of the Philippines) and ELN (in Colombia) are negotiating deals to end their violence. While many leaders of active leftist groups are leaning towards making peace, they often belong to organizations containing some members who want to keep fighting. An example of that can be seen Nepal, the northern neighbor of India, which also had a Maoist rebel movement that, after 2006 technically evolved into a major political party but a small radical faction turned to terror. Other old left rebels, like Shining Patch in Peru have mutated into criminal gangs with a thin veneer of political justification.