When St Paul visited Ephesus around 53 AD, there was a Jewish community at Ephesus for over three hundred years.
At 1st century AD, Jews had spread from their homeland to the Mediterranean and some other places. The oldest Jewish community in Europe is the one in Rome. They were practicing very different religion than their neighbors and as a result of this, Jews were mostly close-knit to protect their faiths and themselves. In Rome, Augustus and Julius Cesar supported Jews to help them to worship as they like and Julius Cesar allowed them to settle anywhere in the Roman Empire. Although they were generally treated with respect, trouble did occur and during the reign of Claudius, Jews had been exiled from Rome two times but than they were allowed to return and continue their independent existence. Each Jewish community worshipped at its own synagogue but the center of their worship is in Jerusalem.
It is known that there have been a substantial Jewish community in Asia Minor since at least the 5th century BC and when St Paul visited Ephesus around 53 AD there was a Jewish community at Ephesus for over three hundred years, but the exact date of the establishment of Jewish community in Ephesus is not known.
Unfortunately there is a little inscriptional evidence for the Jewish community in the ancient city but Ephesus is mentioned as having a synagogue in Acts 19:1 of New Testament. Synagogue hasn’t been found in and around Ephesus but there is a menorah carving on the step of Celsus library.
Source : Ephesus – History, information and pictures of Ephesus Ancient city
The first Christian community in Ephesus was established by St John and developed by St Paul. Paul came in to the city to fulfill the promise that he had given on his brief visit when returning from Corinth and stayed for about three and a half years and also wrote his letters to Ephesians in captivity most probably here in Ephesus. When Paul came to Ephesus, first in the synagogues and then everywhere in the city, he preached the gospel and gained followers. The church of Ephesus which became the head of the Seven Churches in western Asia Minor was established by Paul.
St Paul had to struggle with magicians and soothsayers in Ephesus while struggling with state offices and pagans. In a short time, Ephesus became the third important city of Christianity after Jerusalem and Antioch. Christianity rapidly gained popularity in Ephesus and by the popularity of this new religion, the jeweler Demetrius and others who earned a living by selling and making silver statues of Mother Goddess Artemis, were quite distressed. Demetrius and his colleagues provoked thousands of people and met with them in the Ephesus theatre and started shouting “Great is Artemis of the Ephesians.” St Paul wanted to face the crowd but disciples would not let him. Finally, the city clerk announced that the courts were open for people who had a complaint and dispersed the crowd. After this event St Paul left Ephesus and went to Macedonia.
It is seen that Ephesus had an important place in the lives of both apostles but both of them were not in Ephesus at the same time. John and Paul led different communities in Ephesus.
For travelers interested in biblical sites, Ephesus is especially noteworthy as being the place where St.Paul visited and preached early Christianity to the people.
Source : Ephesus! History, information and pictures of Ephesus Ancient city