Montanus lived in Phyrgia (modern Turkey) in the 2nd century A.D. He is one of the more difficult Christian leaders of the early church to get a handle on because he left no written records himself. However, the renewal movement he initiated lasted long after his death, so it suggests his personality was not as important to the movement as were his teachings and methods.
What we do know is that sometime around 157 A.D. Montanus began teaching in Phyrgia and gained a following. His main emphasis was on speaking prophetic messages from God while in a trance. These ecstatic utterances caused a lot of controversy among church leaders, in part because they had a strong resemblance to pagan practices. In fact, Montanus may have been a pagan priest for the god Cybele before his conversion, as that god was quite popular in that region. Two women, Maximilla and Priscilla, also began giving prophecies with Montanus and they left their husbands to carry out this ministry. He declared their revelations to be from God and called them "virgins of the church," which sounds eerily similar to pagan temple terminology.
By 177 A.D. all the bishops in the neighbouring region, as well as in Rome and France (Gaul), declared Montanus' practices to be heretical and his prophecies to be from Satan rather than from God. However, that did not stop the spread of Montanism. Where they were excommunicated from the Catholic churches, separate Montanist churches sprang up. Even Tertullian defended and joined the Montanists and as a result was excommunicated from the Catholic church.
It seems Montanus' ecstatic methods of delivering the prophecies were the main source of the controversy in the church. There is no record of bishops having any problem with the content of his messages (despite concluding they originated from Satan). Montanists defended their ecstatic methods by pointing to uses of the Greek word for ecstasy in Scriptures. One is Peter's vision in Acts 10:10 where he fell into a trance (ekstasis). Their opponents pointed out that Peter still disagreed with God during the vision ("Surely not, Lord!") so he was not without control of his will. By implication, Montanus must have been losing control of himself while in his prophetic trances.
The Bible is clear that when the Holy Spirit brings a message through a person, that person does not lose control of their will. Paul says in 1 Corinthians 14:32 that "the spirits of prophets are subject to the control of prophets." The Holy Spirit never takes away control of our own behaviour even as He works through us.
The Montanism debate of the second century seemed to condense into two questions, which are still relevant for the church today:
1) How can one know if a prophet is actually receiving a supernatural message or is just pretending to?
2) If it is a supernatural message, how can one know if it is from God or from Satan?
In reality, those two questions boil down to one question: Is the prophecy from God or not? Whether a false prophecy is from the prophet's own imagination (i.e. they are pretending) or from Satan, we do the same thing with it: we throw it out. 1 Thess. 5:19-21 says, "Do not put out the Spirit's fire; do not treat prophecies with contempt. Test everything. Hold on to the good." In the context prophecies, we are not to despise them but rather test them and keep what is good. That means whatever is not good, we do not keep. If a prophecy (or a part of a prophecy) does not line up with the Bible, we throw that part out.
But what about the prophecies that are tested and appear to be from God? What authority do those prophetic words carry? The Montanists believed they could add to and bring clarity to Scripture. The orthodox bishops disagreed. In fact, the Montanist debates showed that churches had already effectively closed the New Testament canon by the late second century in the sense that they had New Testament books they considered to be Scripture and other books that were not of the same authority. The Montanists however used prophetic words to support their theological doctrines in addition to the accepted books of the Bible.
One reason the Montanist churches spread so far and wide was that their behaviour was very Godly. They fasted regularly and celebrated more religious holidays than the mainline church. Sometimes doctrinally they stayed true to Scripture where the Catholic church was veering into error. For example, Tertullian and the Montanists opposed the emerging Catholic practice of bishops absolving people of their sin if they performed sufficient penance, arguing that God was the one to forgive sins and not bishops. Broadbent states (The Pilgrim Church, p. 35) that "the Montanists constantly pressed for definite evidences of Christianity in the lives of applicants for fellowship" in the church, unlike the Catholic bishops who wanted as many adherents in the church as possible.
The story of the Montanists actually sheds some light on how the Catholic church was functioning by the mid-second century:
a) The Catholic church was already in need of renewal; and
b) The Catholic church was lacking the functioning of and direction of the Holy Spirit.
The Montanists sought to correct and strengthen the church in these areas, and like many movements of renewal throughout church history, they made some errors. The Catholic bishops, in correctly identifying those errors, wrongly presumed that everything the Montanists did was therefore wrong. As a result, the Catholic church lost the function of the gift of prophecy and sought to control the working of the Holy Spirit rather than follow Him. Essentially they threw the baby out with the bath water.
