Why was the Jerusalem Council necessary?
The Jerusalem Council was necessary to settle whether salvation comes by faith alone or requires keeping the Law of Moses and circumcision. Paul went up by revelation to confront the Twelve and resolve this debate, so the gospel could move forward into the Gentile world without legalistic requirements.
Les explains that the Jerusalem Council was necessary because even 22 years after Pentecost, the question remained whether a person is saved by faith alone or must keep the Law of Moses and practice circumcision. Paul went up by revelation to Jerusalem to communicate the gospel he preached among the heathen and to confront the Twelve. The issue had to be settled so they could move out into the Gentile world. The council was called to consider this very matter.