Ruth 1:15

Is gone back to her people and to her gods By this it appears, if Orpah had been a proselyte to the Jewish religion, she afterward apostatized. Those that forsake the communion of saints will certainly break off their communion with God. Return thou after thy sister-in-law This she said to try Ruth's sincerity and constancy, and in order that she might intimate to her that if she went with her she must be firm in her attachment to the true religion.