Paul is  writing to the Corinthians from Ephesus during the fall of 55 AD or the spring  of 56 AD. Timothy and a delegation have been sent to Corinth, but Apollos was  unwilling to go back with the delegation even though Paul urged him to go and  the Corinthians were asking for him (1  Corinthians 16:10-12). The delegation that is traveling with Timothy to  Corinth are leaders of the Corinthian  
                              church that had traveled to Ephesus to  meet with Paul and are identified in 1  Corinthians 16:17 (Stephanas, Fortunatus and Achaicus) and are also  mentioned in 1  Corinthians 1:11. The delegation 
is returning to their church in Corinth with  Timothy and a letter from Paul that we  
call First Corinthians. 
                              In this  letter Paul told the Corinthians that his plans were to stay in Ephesus until  Pentecost 
(between May 16–June 13) in the spring of 56 AD (which would be 50  days after the Jewish Feast 
of Passover held between March 26-April 24). Paul stayed  in Ephesus a few more months before he left for Corinth. Once Paul is in  Corinth, he will try to leave for Jerusalem before Pentecost in the spring of  57 AD at the end of his third missionary journey according to Acts  20:16 . 
                              The reason  Paul sends Timothy to Corinth with the delegation from Corinth is “because a  great  
                                door for effective work has opened” for him in Ephesus and the  surrounding cities of Asia. It would appear that it was during this time that  the churches of Colossae, Smyrna, Laodicea, Philadelphia, etc. were started.  The effective work of Paul and the Ephesians at this time is described in  
                                Acts  19:9-10: 
                              
                                "He took the disciples with him  and had discussions daily in the lecture hall of Tyrannus. This went on for two  years, so that all the Jews and Greeks who lived in the province of Asia heard  the word of the Lord.” – Acts 19:9-10 
                               
                              Not only was  there “a great door for effective work” in Ephesus, Paul also says, “there are  many  
                                who oppose me.” It seems Paul was anticipating the conflict stirred up by  Demetrius that would 
                                result in the riot that drove Paul out of Ephesus a few months  after the letter of First Corinthians 
                                was sent, because this opposition  eventually resulted in the riot of Acts  19:23-41. The 
  “effective work” of the ministry altered the cultural and  spiritual climate of Ephesus to the point 
                                that the economy created by the sale  of the silver idols produced by Demetrius and the other craftsmen was seriously  impeded. The presentation of Bible teaching and the apostolic doctrine 
                                on a  daily basis to the believers in Ephesus changed their lives, their culture and,  then, reached  
                              into the surrounding cities of Asia.  |