one of their own prophets: This quotation is from Epimenides of Knossos, a philosopher who lived on Crete around the 500s BC.
liars: This charge was directed specifically at the Cretan claim to have Zeus’s tomb on the island. According to Cretan mythology, the god Zeus was once a mere human who lived and died on Crete. His tomb was said to be there. But Zeus had achieved godhood through his patronage (that is, gifts and benefits) to humans. Some Greek moralists opposed this legend and characterized it as a lie. A quote from Alexandria in the 200s BC reads: “Cretans are always liars. For a tomb, O Lord, Cretans build for you; but you do not die, for you are forever.” One of Crete’s own prophets (Epimenides) thought the same thing. Paul cites his voice of conscience approvingly (Titus 1:13; see Acts 17:28), for the God who does not lie (Titus 1:2) opposes the lies of such myths.
liars … beasts … gluttons: It was believed that Cretan immorality resulted from their belief about Zeus. Religious lies had led to moral corruption. Paul later counters these vices by presenting the contrasting virtues (positive qualities or behaviors) (Titus 2:12). He urges the Cretans to reach ethical ideals that are praised in human society generally but were absent on Crete, as bemoaned by their own prophet. They would reach these ideals only through the gospel of Jesus Christ (2:11–14).
lazy gluttons: Cretans were known to do anything for money. They were well-known as mercenaries and as excessive consumers. They were said to feel no shame in their greed (see Philippians 3:19).
Paul applies the quotation more directly to the current false teachers than to Cretan culture generally. The false teachers carried on this Cretan tradition of immorality based on a lie.