Sosthenes, from the Greek pronounced soce-then-ace, meaning safe in strength, was "the chief ruler of the synagogue" at Corinth at the time that the apostle Paul (see Paul's Ministry) preached in the city. After refusing to prosecute (i.e. persecute) Paul at the demand of the unbelieving members of the synagogue, Sosthenes was beaten as a demonstration of how, in Satan's thug-based world, whoever has the most brute force is always "right" - even if what they do is arrogantly hypocritical and repulsively evil for all to see. Gallio, the Roman governor of the occupied city (see Ancient Empires - Rome) refused to stop the violence (see Violence to understand the Biblical meaning of that word) because "it be a question of words and names, and of your law, look ye to it; for I will be no judge of such matters."
Although not certain, it is at least very possible that the same Sosthenes was the man mentioned in Paul's later epistle (see Epistles) to the church at Corinth:
"1:1 Paul, called to be an apostle of Jesus Christ through the will of God, and Sosthenes our brother, 1:2 Unto the church of God which is at Corinth, to them that are sanctified in Christ Jesus, called to be saints, with all that in every place call upon the name of Jesus Christ our Lord, both theirs and ours: 1:3 Grace be unto you, and peace, from God our Father, and from the Lord Jesus Christ. 1:4 I thank my God always on your behalf, for the grace of God which is given you by Jesus Christ; 1:5 That in every thing ye are enriched by him, in all utterance, and in all knowledge; 1:6 Even as the testimony of Christ was confirmed in you" (1 Corinthians 1:1-6 KJV)
"Then all the Greeks took Sosthenes, the chief ruler of the synagogue, and beat him before the judgment seat"
It was at Corinth that Paul also met Priscilla and Aquila who had been driven out of Rome. Corinth is located about 50 miles / 80 kilometers west of Athens, on the narrow isthmus that connects the southern section of Greece, known as the Peloponnesus, to the Greek mainland. The city name has become well-known to Christians from the two epistles that the apostle Paul later wrote to the Christians there - First and Second Corinthians.
"18:1 After these things Paul departed from Athens, and came to Corinth; 18:2 And found a certain Jew named Aquila, born in Pontus, lately come from Italy, with his wife Priscilla; because that Claudius had commanded all Jews to depart from Rome: and came unto them. 18:3 And because he was of the same craft, he abode with them, and wrought: for by their occupation they were tentmakers. 18:4 And he reasoned in the synagogue every sabbath, and persuaded the Jews and the Greeks.
Fact Finder: (a) What happened during Paul's first missionary journey? (b) What happened during Paul's second missionary journey? (c) What happened during Paul's third missionary journey? (d) What happened during Paul's voyage to Rome as a prisoner of the Romans?