Pope Francis decried what he called a genocide against Christians in the Middle East while speaking in Bolivia on Thursday."Today we are dismayed to see how in the Middle East and elsewhere in the world many of our brothers and sisters are persecuted, tortured and killed for their faith in Jesus," he said. sign up to our newsletter"In this third world war, waged piecemeal, which we are now experiencing, a form of genocide is taking place, and it must end."His speech in Bolivia was part of a trip to Ecuador, Bolivia and Paraguay, three of South America's poorest and smallest countries.Modern-day religious persecution has been a common theme that Pope Francis tackles as its incidences in the Middle East rise and become more brutal.In February, 21 Egyptian Christians believed to be held by Islamic State were murdered. In a video of the killing, militants in black marched the captives, dressed in orange jump suits, to a beach the group said was near Tripoli. They were forced down onto their knees, then beheaded. The video was then shared via the internetOn April 19, another video purportedly made by Islamic State and posted on social media sites showed militants shooting and beheading about 30 Ethiopian Christians in Libya.At Good Friday services on April 4, he said that "We see in you our persecuted brothers, beheaded and crucified because of their faith in you, before our eyes or often with our complicit silence."Reuters contributed to this report.