Certainty is the great enemy of unity. Certainty is the deadly enemy of tolerance. Even Christ was not certain at the end: Dio mio, Dio mio, perché mi hai abbandonato. He cried out in his agony at the ninth hour on the cross. Our faith is a living things precisely, because it walks hand-in-hand with doubt. If there is only certainty and no doubt, there would be no mystery, and therefore no need for faith.