On the evening of 24 May 1738 John Wesley reluctantly attended a meeting at Aldersgate Chapel where a lay persons was reading from Martin Luther's Preface to Paul's Letter to the Romans. During this reading Wesley experienced that "he felt his heart strangely warmed." The assurance of his salvation by God came to him. God drew near to Wesley in this simple service.
Charles Wesley had his own "Aldersgate" experience three days earlier on 21 May 1738.
These two brothers were the moving and organizing force for the Methodists. John traveled, preached, and organized. Charles also traveled and preached - but not nearly as much as John.
Charles Wesley was the prolific writer of hymns; and he put the Methodist doctrine into songs.