Pope Francis is telling Christian and Muslim leaders in Kenya that they have little choice but to engage in dialogue to prevent the "barbarous" Islamic extremist attacks that have struck Kenya recently.

On his first full day in Africa, Francis insisted Thursday that religion can never be used to justify violence and lamented that "all too often, young people are being radicalized in the name of religion to sow discord and fear, and to tear at the very fabric of our societies."

He said interfaith dialogue isn't a luxury or optional, but is simply "essential."

Francis made the comments in a meeting with Kenyan faith leaders at the start of a busy day that will see him celebrate Mass on a rain-soaked university campus and deliver a major environment speech.