One of the first challenges faced by the early church is discussed in the book of Galatians. Simply put, the question was this: were converts to the Christian faith saved by keeping the law?
Paul’s answer to this question was No. The only sound basis for life in Christ was faith. In no other way could a person be made right with God, certainly not through any merit earned by law-keeping.
Apparently, the churches in Galatia contained some teachers who disagreed with Paul on this point. So Paul felt he must assert his authority in this letter. In the first part of Galatians, he claimed that he was an apostle appointed by Jesus Christ and was commissioned to give His message.
The last part of Galatians shows how faith results naturally in proper Christian conduct.