On the first Sunday of the 2015 Edinburgh Fringe, the stage of the Traverse Theatre turned into a church: in front of a huge illuminated crucifix stood a Pentecostal choir in purple cassocks swayingly singing the revivalist anthem “Catch on Fire”.In The Christians, an American play by Lucas Hnath that is receiving its European premiere at the Scottish festival, members of Edinburgh’s SongWorks community choir have been seconded to represent a Southern Baptist congregation on the day that they celebrate paying back the final instalment of the bank loan borrowed to found their church.But, as Pastor Paul (William Gaminara) delivers his sermon, he reveals that prayer and Bible-reading have convinced him that Hell does not exist and that all who die receive God’s mercy: