The Montanists were a charismatic group who had many strange doctrines including believing in Venal sins and mortal sins later incorporated into the RCC.
The important thing to remember when researching ancient dissenters is that the winner always writes the history books.
There is no doubt that some, or even most, Montanists were what we might call "charismatics."
However, when we look at all those who fly the standard of "Baptist" we will also discover some serious irregularities, including charismatic practices. But that cannot be legitimately applied to all Baptists without distinction.
It is claimed that Montanus said he was the Paraclete, and that his followers claimed extra-Biblical revelations. Unfortunately there is no proof to support these charges. The spirituality and life of Montanist churches so contrasted with the formality and deadness of the main-stream churches, that such conclusions may easily have been drawn. If a Roman Catholic or High Anglican came to a Bible-believing Baptist church today, he would probably think it was very emotional too, what with strong preaching, contemporary music, pianos, drumbs, and often an invitation at the end!
The Lutheran historian Mosheim accuses Montanus of calling himself the Paraclete, but the translator of his history, McLean, adds the following footnote: "Those are undoubtedly mistaken who have asserted that Montanus gave himself out that he was the Holy Ghost" (Church History, Mosheim, Volume I, Page 188).
Armitage concludes, "For this reason Montanus was charged with assuming to be the Holy Spirit, which was simply a slander" (Armitage, T.; A History of the Baptists, page 175).
W. A. Jarrell cites Tertullian's explanation of an "ecstasy" and concludes that he probably meant nothing more than what David said - "My cup runneth over."
Tertullian, referring to visions and extra-Biblical revelations said: "But truly according as the Scriptures are read, or Psalms are sung, or addresses are given, or prayers are offered, thence, from that medium are materials by which we are assisted by visions." The context of this statement clearly indicates what we would call "illumination" today. Nothing "extra-Biblical" about that! It is generally admitted that the Montanist churches accepted the received doctrines of the "established" church - their only differences being that of emphasis and practice.
It is possible, but not conclusively proven, that some Montanist churches did hold to questionable or unscriptural practices, such as some condemn, the ordination of women. Some churches may have allowed women to preach because of their belief that the gifts of the Holy Spirit are dispensed to Christians of every condition and sex, without distinction.
Triune immersion may have been practiced in some Montanist churches.
Some of the Montanist Pastors may have remained celibate, but no conclusive statement to that effect can be found, however, it may have been the more practical precaution in time of persecution according to 1 Corinthians 7:26-29 (compare to verses 8 and 9).
They were accused of practicing harsh asceticism by those who lived very liberal life styles, and that they practiced harsh church discipline. It should be noted that each of these practices, even if true, are not unknown in some Baptist churches today.
The preaching of the Montanists had far ranging results. Tertullian was a noted convert to Montanist ideals, who helped to refine those teachings and left a legacy in North Africa (Tertullianists) which would later give rise to the Donatists.
Several church councils were called against the Montanist movement, and it was finally officially condemned by the "established" churches. The influence of this movement may be seen in the Novatian schism, the Donatus schism, and through its contacts in Armenia and the rise of the Paulicians.
Several defenders among historians may be found for the Montanists, some of whom are cited here:
1. The conclusion of an early historian, Dr. William R. Williams, is that it was hard to find doctrinal errors in their teaching. Their emotionalism stemmed from their belief that a true experience of grace is evident in the believers life, as many other teachers have stressed in much later periods of reform.
2. Dr. Dorner wrote of their movement that it was a democratic reaction of the church members against the movement to install church leaders as overlords in the church body.
3. Moller, contributor to the Schaff-Herzog Religious Encyclopedia, wrote, "But Montanism was, nevertheless, not a new form of Christianity; nor were the Montanists a new sect. On the contrary, Montanism was, simply a reaction of the old, the primitive church, against the obvious tendency of the day, to strike a bargain with the world and arrange herself comfortably in it." (Quoted from : Griffith, J. W., A Manual of Church History: Volume II, page 36).