Sosthenes is one of the interesting ‘background’ characters who appears in the New Testament. He appears in the book of Acts, where it notes:
Then the crowd there turned on Sosthenes the synagogue leader and beat him in front of the proconsul; and Gallio showed no concern whatever.
We learn from this that Sosthenes was a Synagogue leader, and was beaten before the proconsul. There is a confusion here about who precisely beat Sosthenes, as he was the chief ruler of the synagogue – but the passage could be interpreted to say that the Greeks beat him, or that the ‘Jews’ beat him. Adam Clarke writes:
Then all the Greeks took Sosthenes – As this man is termed the chief ruler of the synagogue, it is probable that he had lately succeeded Crispus in that office; see Act 18:8; and that he was known either to have embraced Christianity, or to have favored the cause of St. Paul. He is supposed to be the same person whom St. Paul associates with himself in the first epistle to the Corinthians, 1Co 1:1. Crispus might have been removed from his presidency in the synagogue as soon as the Jews found he had embraced Christianity, and Sosthenes appointed in his place.
And, as he seems to have speedily embraced the same doctrine, the Jews would be the more enraged, and their malice be directed strongly against him, when they found that the proconsul would not support them in their opposition to Paul.
But why should the Greeks beat Sosthenes? I have in the above note proceeded on the supposition that this outrage was committed by the Jews; and my reason for it is this: Οι’Ελληνες, the Greeks, is omitted by AB, two of the oldest and most authentic MSS. in the world: they are omitted also by the Coptic and Vulgate, Chrysostom, and Bede. Instead of Οι’Ελληνες, three MSS., one of the eleventh, and two of the thirteenth century, have Ιουδαιοι, the Jews; and it is much more likely that the Jews beat one of their own rulers, through envy at his conversion, than that the Greeks should do so; unless we allow, which is very probable, (if Ελληνες, Greeks, be the true reading), that these Hellenes were Jews, born in a Greek country, and speaking the Greek language.
~Adam Clarke’s Commentary on the Bible
The irony of Sosthenes’ becoming a Christian is palpable given that he succeeded Crispus as the chief Rabbi of the synagogue, Crispus having been removed precisely because he accepted Christianity and was Baptized by Paul (1 Corinthians 1:14). Note that Crispus’ removal demonstrates that even very early on there was a faction of the Pharisees who targeted and dis-fellowshiped Christian Jews from the Synagogue (thus making John 9:22 much more historically plausible). Paul later writes to the Corinthians with this greeting:
Paul, called to be an apostle of Christ Jesus by the will of God, and our brother Sosthenes, to the church of God in Corinth, to those sanctified in Christ Jesus and called to be his holy people, together with all those everywhere who call on the name of our Lord Jesus Christ—their Lord and ours.
~1 Corinthians 1:1-2
Obviously Sosthenes had become a Christian by this point (and was not merely a Christian sympathizer). Sosthenes, like Crispus, Nicodemus, Joseph of Arimathea, Paul, and even, to some extent, Gamaliel (Acts 5:34) who was Paul’s Rabbinic instructor (Acts 22:3) and about whom the Mishnah says that when he died some of the glory of Torah died with him:
WHEN RABBAN GAMALIEL THE ELDER DIED, THE GLORY OF THE TORAH CEASED, AND PURITY AND ABNEGATION PERISHED.
~ Babylonian Talmud, Tractate Sotah, Mishnah, Folio 49a
serves as an example of just how ‘Jewish’ Christianity was and has always been in essence.