Irenaeus's model of a single true Christianity from which heretics diverged readily accounts for both of these factors. According to this view, there always was a single true orthodox faith, and any Christian "diversity" simply reflects demonically inspired heretical movements. Modern
versions of this model allow that "mainstream" Christianity may have changed and developed over the centuries, but they still insist that a core set of Christian beliefs persisted within this mainstream and that groups like the Montanists and the Valentinians strayed from these basic beliefs in various ways.
