Clerics who are self-righteous and over-intellectualise religion can end up hurting and ostracising sinners who do repent, Pope Francis said at his morning Mass.

Such priests uphold their own rules and "erase the law made by the Lord," who told Abraham to "walk in my presence and be blameless," the Pope said on December 13 during the Mass in the chapel of the Domus Sanctae Marthae, where he lives. It was the 47th anniversary of the Pope's ordination as a priest.

The Pope focused his homily on the day's reading from the Gospel of Matthew (21:28-32) in which Jesus asks the chief priests and elders which of two sons did his father's will: the one who refused to work in the vineyard, but then changed his mind and did, or the son who said he would work, but did not.