ROME — Pope Francis, presiding at the traditional Good Friday Colosseum procession, decried what he called the “complicit silence” about the killing of Christians. The evening, torch-lit ceremony at the ancient arena recalls the suffering and death of Jesus by crucifixion. After listening silently, often with head bowed and eyes tightly shut, to reflections read aloud about Jesus’ suffering, Francis pressed what lately has been an urgent concern of his papacy — the present-day martyrdom of Christians in parts of the Middle East, Africa and elsewhere. “We see, even today, our brothers persecuted, beheaded and crucified, for their faith in you, in front of our eyes or often with our complicit silence,” he said, as he prayed. A few hours earlier, Francis had condemned the deadly attack by Islamic militants targeting Christians at a Kenyan university.