The Communion Test
In years of attending non-denominational, evangelical churches, I grew accustomed to some version of a pre-Communion caveat: "If you have accepted Jesus Christ as your savior and are a member of the body of believers, whether this is your home church or not, you are welcome to partake of the bread and the cup. Seekers and young children can let the elements pass by." Sometimes unconfessed sin gets mentioned, too, but usually the issue is personal salvation.
I know other churches have different conventions (I was once denied Communion when visiting a mainline church, for reasons I've never completely understood), but the familiar restrictions always seemed pretty reasonable to me. That wasn't the case 250 years ago. When Puritan pastor Jonathan Edwards launched "An Humble Inquiry into the Rules of the Word of God Concerning the Qualifications Requisite to a Complete Standing and Full Communion in the Visible Christian Church," his Northampton, Massachusetts, congregation fired him—June 22, 1750.
The era in which Edwards ministered saw sweeping changes in the Christian experience. In England, the Wesley brothers defied the Church of England's geographic definition of ministry by preaching all over the country and encouraging people to meet for spiritual enrichment outside the walls of the parish church. George Whitefield stirred crowds on both sides of the Atlantic into a frenzy by telling people to search their hearts for the feelings of faith. The dramatic conversions of individual men, women, and children received unprecedented attention. Membership in a church body was still important (John Wesley considered himself a loyal Anglican to his death), but the sense of "religious self" was definitely on the rise.