Albert Barnes Commentary Romans 2:19

"and art confident that thou thyself art a guide of the blind, a light of them that are in darkness," — Romans 2:19 (ASV)

And art confident. This expression denotes the full assurance of the Jew that he was superior in knowledge to all other people. It is a remarkable fact that the Jews put the fullest confidence in their religion. Though proud, wicked, and hypocritical, they were not speculative infidels.

It was one of their characteristics, evinced throughout all their history, that they had the fullest assurance that God was the Author of their institutions and that their religion was his appointment.

A guide of the blind. A guide of the blind is a figurative expression to denote an instructor of the ignorant. The blind here properly refers to the Gentiles, who were thus regarded by the Jews. The meaning is that they esteemed themselves qualified to instruct the heathen world, Matthew 15:14; Matthew 23:16.

A light. Another figurative expression to denote a teacher. (John 1:4, 5, 8, 9).

In darkness. A common expression to denote the ignorance of the Gentile world. (See Barnes on Matthew 4:16).