Question: I have a question regarding Acts 18:8,17. There seems to be a contradiction, as Verse 8 says that Crispus is the chief ruler of the synagogue and Verse 17 says that Sosthenes was the chief ruler of the synagogue.
Answer: Paul was in Corinth for a year and a half ; and, no doubt, Sosthenes succeeded Crispus as chief ruler of the synagogue. There is no contradiction.
Taking into consideration the entire context of Acts, Chapter 18, here is the account. This is Paul’s first visit to Corinth and “he reasoned in the synagogue every sabbath and persuaded the Jews and the Greeks…Paul was pressed in the spirit, and testified to the Jews that Jesus was the Christ.” (Acts 18:4,5). He was immediately and violently opposed by the Jews,
“And when they opposed themselves, and blasphemed, he shook his raiment, and said unto them, Your blood be upon your own heads; I am clean: from henceforth I will go unto the Gentiles.”
However, the Word of God had taken its effect,
“And Crispus, the chief ruler of the synagogue, believed on the Lord with all his house; and many of the Corinthians hearing believed, and were baptized."
Notice, baptism came after believing!
When Gallio, the new deputy of Achaia, arrived, all the unbelieving Jews took their opportunity and brought Paul before the judgment seat,
“Saying, This fellow persuadeth men to worship God contrary to the law.” - Acts 18:13
They thought they would end Paul’s preaching about Christ once and for all! As Paul was about to defend himself,
“Gallio said unto the Jews, If it were a matter of wrong or wicked lewdness O ye Jews, reason would that I should bear with you: But if 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. And he drave them from the judgment seat.” - Acts 18:14-16.
When the Greek bystanders saw Gallio’s rude treatment of the Jews,
“...all the Greeks took Sosthenes, the chief ruler of the synagogue (who succeeded Crispus), and beat him before the judgment seat.”
The Bible tells us,
“And Gallio cared for none of these things.” (Acts 18:17).
The only law that Gallio cared about was Roman law.
Perhaps Sosthenes had been elected chief ruler of the synagogue because Crispus had become a Christian. His persecution came because he was a Jew and associated with the synagogue. Paul’s persecution came from his bold witness for the Lord Jesus Christ. Sosthenes also may have become a believer, and when Paul left Corinth he went with him. We find in the salutation to 1 Corinthians the following greeting,
“Paul, called to be an apostle of Jesus Christ through the will of God, and SOSTHENES, OUR BROTHER, Unto the church of God which is at Corinth.” - 1 Corinthians 1:1
Can we say, as did Paul,
"For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek."- Romans 1:16