Pope Francis is warning people against the dangers of "subtle sin" and even said that not all churchgoers are good people.

In a homily delievered at the chapel of Saint Martha residence in the Vatican, Pope Francis shared the parable of the rich man and Lazarus, which is found in the Gospel of Luke.

The rich man boasted of fine clothing and ate lavish meals, while Lazarus was a beggar who lived near his house, struggling with hunger and diseases. Pope Francis explained that the rich man was not really evil, but "the eyes of his soul were certainly tinted so as not to see."

"Maybe he was a religious man, in his own way," the Pope said. "Maybe he prayed and a couple times a year he surely went up to the temple to offer sacrifices and he gave big donations to the priests, who in their clerical cowardice would thank him and give him a seat of honour."

But it did not matter what "good deeds" he made in honour of the church. The rich man still failed to recognise the plight of the poor man who was living so close to his home.

Pope Francis then applied the parable to modern times, warning that a lot of people are religious but their hearts are overshadowed by worldliness, and so they fail to witness the suffering of the people around them.

"With a worldly heart you can go to church, you can pray, you can do many things," Pope Francis said. "But if your heart is worldly you cannot understand the needs and hardships of others."

He called this blindness not only a "subtle sin," but "a sinful state of the soul."

"There is a curse on the person who trusts in the world and a blessing on the one who trusts in the Lord. The rich man's soul is a desert and an inhabitable wasteland," he said, adding that worldly people "are alone with their selfishness."

But the Pope said that there is still hope. "We have a father who waits for us. In the midst of our worldliness, He calls us his children. We are not orphans," he said.