Acts 18:8

8. Crispus Their most eminent man, became a Christian with all his house. (See note on 1 Corinthians 1:14.)

Of course his secession from Judaism was a vacation of his office; and it seems probable that Sosthenes, (Acts 18:17,) who was a leader of the party opposed to Paul, forthwith stepped into his place. He suffered the penalty of a flogging for his ambition, and perhaps became a Christian, the “Sosthenes the brother” of 1 Corinthians 1:1.

Many of the Corinthians Probably Jews and Gentiles, with a majority of the latter.