(CNN) Christians who exploit people, lead a double life and get involved in "dirty business," scandalize the church, Pope Francis said in a sermon Thursday in Rome. In fact, it might be better just to be an atheist.

"And so many Christians are like this, and these people scandalize others. How many times have we heard -- all of us, around the neighborhood and elsewhere -- 'but to be a Catholic like that, it's better to be an atheist.' It is that, scandal. You destroy. You beat down," Francis said, according to Vatican Radio.

Examples of such scandals abound, the Pope said, adding that they erode the church and the guilty Christian from within, by causing others to sin and lose faith.

Francis' sermon, as is customary, was an extended riff on Thursday's Mass readings, which include a passage from the Gospel on Mark in which Jesus says it is better to be drowned than to cause others to sin.