Original sentence: This presented a problem for the heresiologists writing on gnostic movements: this mode of behaviour was one they themselves favoured and supported, so the Church Fathers, would be required perforce to offer support to the practices of their theological opponents
Edited sentence: This presented a problem for the heresiologists writing on gnostic movements: this mode of behaviour was one they themselves favoured and supported, so the Church Fathers, some modern-day Gnostic apologists presume—would be required perforce to offer support to the practices of their theological opponents