What was Paul doing during the three years alone before he preached?
During that three-year period, Paul was shedding Judaism and its religious demands and absorbing the doctrines he later set forth in his prison epistles. He was being set free from legalism and receiving revelations, which were fresh when he later wrote from Rome.
Les teaches that Paul had been weighed down with Judaism and all its demands as a religious leader, but he had now been set free. During the three years, Paul had time to shed himself of all that and to absorb the truths he later brings out in his prison epistles—Ephesians, Philippians, Colossians, and Philemon. Les suggests these revelations were probably given to Paul while he was in prison in Caesarea before he reached Rome, so that by the time he got to Rome the new revelations were fresh on his mind as he wrote those letters. Even in his earlier epistles, Les notes, these tremendous doctrines are separated from legalism and Judaism, yet they all fit together and are not a thorn in the rest of Scripture.