Pope Francis on Sunday said clergy and Christians must not betray the word of God with their actions or they undermine the credibility of the Catholic Church.

Francis, elected a month ago, inherited a Church struggling to restore credibility after a series of scandals, including the sexual abuse of children by priests.

The pope spoke at the Papal Basilica of St. Paul’s Outside the Walls, where he celebrated Mass. He also greeted pilgrims and local Church members earlier in St. Peter’s square.

“Inconsistency on the part of pastors and the faithful between what they say and what they do, between word and manner of life, is undermining the Church’s credibility,” the pontiff said in his homily.