Where did Paul receive the revelations of the doctrines of grace?
Paul received the revelations of the doctrines of grace at Mount Sinai in Arabia. Just as Moses received the Law there, Paul went to the same mountain and received these revelations, then carried them to the Gentile world rather than to Israel.
Les explains that Paul went to Mount Sinai in Arabia, the same mountain where God gave the Law to Moses. There Paul received all the revelations of the doctrines of grace, but unlike Moses he did not take them to Israel; he took them to the Gentile world. Les also notes Paul spent three years there alone with the Lord Himself, which answered the Corinthians' charge that Paul lacked the three years Peter had with Jesus.
For this Agar is mount Sinai in Arabia, and answereth to Jerusalem which now is, and is in bondage with her children.
More Questions
Why did God reveal the doctrines of grace to Saul at Mount Sinai in Arabia?
Because Hagar is identified with Mount Sinai in Arabia, the same place where God gave the Law to Moses, God fittingly took Saul there to reveal the doctrines of grace.