VATICAN CITY (CNS) — Christianity isn’t a school for teaching a superficial form of being nice to everyone, but it’s also not a boot camp where everything is rigidity, rules and long faces, Pope Francis said.

“The Lord calls us to build our Christian life on him, the rock, the one who gives us freedom, the one who sends us the Spirit, who keeps us going with joy on his path, following his proposals,” the pope said June 27 during his morning Mass in the Domus Sanctae Marthae.

According to a report by Vatican Radio, Pope Francis warned in his homily that too many people today “masquerade as Christians,” rejecting either the challenging teachings of Christ and his Gospel or rejecting the joy and freedom the Holy Spirit brings.

“In the history of the church there have been two classes of Christians: Christians of words — those who say, ‘Lord, Lord, Lord’ — and Christians of action, in truth,” the pope said.

The Christians who are all talk, he said, fall into two opposing categories: those he defined as “gnostics,” who “instead of loving the Rock, love pretty words” and follow a “liquid Christianity” without substance; and those he defined as “Pelagians,” who “believe that the Christian life must be taken so seriously that they end up confusing solidity and firmness with rigidity. They are rigid! They think that being Christian means being in perpetual mourning.”

Both groups, he said, are missing the key connection to Christ, “the only one who sustains us in difficult times.”

“They do not know how to enjoy the life that Jesus gives us because they do not know how to talk to Jesus,” the pope said. Because they have no joy, they have no freedom either. They are “slaves of superficiality” or “the slaves of rigidity.”