Ecclesiology comes from two Greek words, that means "Assembly" and "word", which combined means "study of the church".
One of the earliest ecclesiological issues facing the Christian community was with the Jewish people and the Gentile believers of Christ, At the time, many people who became believers in Christ were called Jews. Once the Gentiles started to gather more people they didn't want to become Jews because of circumcision. The problem was however that you had to be circumcised in order to become a full believer. At the council of Jerusalem, they determined that they did not have to be circumcised but they needed to honor the Jewish commands. Then, Paul came out and said that the Gentiles needed to be circumcised. They argued if the Jewish people should be able to eat at the same table as Gentiles. Eventually the whole situation ended and Christianity came to be a Gentile Religion until the Israelites became the people of God. 
What is Ecclesiology?
- Ecclesiology New World Encyclopedia Unknown Author. Web. Accessed on January 17, 2019.