Was Tertullian really a heretic by the prevailing (orthodox) standards of his day and those standards which obtained a century or so later? Interestingly, a number of scholars are now answering this question with a resounding "nay!"
One powerful line of evidence that suggests Tertullian never stopped being "catholic" is the fact that (for a time) Cyprian of Carthage evidently read nothing but the works of Tertullian. He in fact called him "the master" and tried to emulate his approach vis-à-vis theological and salvific issues (Vide Jerome, De Viris Illustribus, Chapter 53).
Yet there are other lines of evidence that indicate Tertullian, by the standards of orthodoxy prevailing during his time and shortly thereafter, was not a heretic.
T. Barnes writes: "Tertullian's later writings receive abuse and condemnation in subsequent ages. Many of the charges are unmerited"(83). He concludes that Tertullian was bold enough to sound forth an "unpalatable truth," namely, that "the church is not a conclave of bishops" but functions as the ordained locus of the Holy Spirit. In other words, where the Spirit of God is, there is the church (Ibid., 83-84). Cf. Pudicitia 21.17:
"And accordingly 'the Church,' it is true, will forgive sins: but (it will be) the Church of the Spirit, by means of a spiritual man; not the Church which consists of a number of bishops (ecclesia spiritus per spiritalem hominem, non ecclesia numerus episcoporum). For the right and arbitrament is the Lord's, not the servant's; God's Himself, not the priest's."
William Tabbernee believes it is "highly unlikely" that Tertullian "ever separated from the catholic church at all." He also argues that the fiery Carthaginian surely did not found the group known as the Tertullianists, a post-Montanist sect (475-476). While Tertullian's works are supposedly condemned by Pope Gelasius in the Decretum Gelasianum, patristic scholars note that this document could be forged (Cf. J. Quasten).