Pope Francis has condemned employers who exploit their workers by offering only temporary contracts or not providing health insurance, calling them "true leeches [that] live on the bloodletting of the people they make slaves to work."
Reflecting Thursday on the day's Mass readings during his homily at Casa Santa Marta, the pontiff also said that Christians err when they think there is a "theology of prosperity" in which God "sees that you are just and gives you much wealth."
"You cannot serve God and wealth," the pope said, reflecting on a passage from the letter of James in which the early disciple warns that the wealthy will one day "weep and wail" and that their riches will rot away.
While wealth can be a good thing if it is used for good ends, it can also become like a "chain" that pulls us away from being free to follow Jesus, said Francis.
The pope imagined a scenario in which an employer offers work to someone from September to June, without the possibility of a pension or health insurance. For July and August that person "must eat air," said the pontiff.
Rephrasing James' warning, Francis said: "The blood of all the people that you have sucked dry ... is a cry to the Lord, a cry of justice. Exploitation of people today is a true slavery."
"We thought that slaves do not exist anymore," said the pontiff. "They exist. It's true, people don't go to Africa to take them and then sell them in America, no. But it's in our cities."
"Living off the blood of the people: This is a mortal sin," said the pope. "It is a mortal sin. And it takes much patience, much restitution to convert ourselves from this sin."
Francis recalled that funeral of a man that he said "was ruined" because "they could not close the casket."
"He wanted to take with him all that he had, and he couldn't," said the pope. "No one can bring their wealth with them."
"Let's think of this drama of today," said the pontiff. "The exploitation of people, the blood of this people that becomes slaves, the traffickers of people and not only those that traffic prostitutes and children for child labor, but trafficking that's more, let's say, 'civilized.'"
The pope then mimicked an employer who says: "I will pay you this much, without vacation time, without health insurance, all under the table -- but I will become rich!'"
"May the Lord make us understand today that simplicity that Jesus tells us in the Gospel today," asked Francis, before rephrasing Thursday reading from Mark's Gospel: "A glass of water in the name of Christ is more important than all the wealth accumulated by exploitation of people."