Although there was much persecution during the first centuries of the church's life, it was also a time of much internal growth. The church was shaped during this time. It was shaped with respect to doctrine and organization.

Is doctrine important? Many people think it is not: as long as you live a decent life; what you believe does not matter so much. Of course, the result of this approach is great ignorance of Christian truth. It is one of the devil's tricks in his never ending attempt to destroy the church. Especially when the church was young and fragile, there were many attacks on the truth and it took the church several hundred years to lay out the fundamental doctrines — things which we take for granted. In this development various classes of men played key roles.

The Apostolic Fathers — took the place of the apostles. Taught by the apostles themselves, they lived in the first half of the second century. There were seven — we know the names of five: Clement and Hermas (of Rome); Ignatius of Antioch; Polycarp of Smyrna; Barnabas of Alexandria. From their writings we can tell their understanding of truth was not yet very deep and their conception of Christianity was simple. They thought of Christ mainly as the revealer of knowledge of the true God and the proclaimer of a law of strict morality.

The Apologists — wrote defenses ("apologies") against some of the heathen attacks. Early believers were accused of doing the most outrageous things and of holding the strangest beliefs. To refute these attacks, men studied the Bible and gave their answers. In this way, understanding of Scripture truth grew and a body of beliefs was forming. Justin Martyr was the leading Apologist. He was beheaded around 165 AD in the city of Rome.

Heretics — In the last part of the second century two heresies troubled the church greatly. Remember, this was at a time when many teachers were floating around, bringing their own versions of the gospel and sometimes telling rather strange tales. Who could always know for sure what was right?

Gnosticism — The first heresy is that of Gnosticism (from Greek gnosi — knowledge). Salvation from this evil world, rather than from sin, would be by knowledge rather than by faith. It was not an organized movement but a system of beliefs and thoughts which held:

1. There is an Old Testament evil God of war and revenge who created this evil world;
2. There is a New Testament God of spirit and light;
3. Jesus Christ came from this good God and appeared on earth to teach some people how to escape from this evil, material world;
4. Inside each person there is locked away a good spirit;
5. Sex and marriage are wrong for they imprison more souls;
6. There is no resurrection of the body.

Gnosticism, because it was not organized and because it used the language of faith ("Jesus is Lord and Saviour) fooled many people. Some of its ideas are still present today and have recently come to the fore in the New Age" movement.

The Canon of Scripture and Creeds — In the struggle against this, the church began to draw up a list of books which were "canonical" (i.e. they measured up to the standard) and it began to formulate some basic creeds. Some of the greatest names in this were Irenaeus, a bishop in France, and Tertullian, a lawyer from North Africa. In time, through defining the canon (i.e. the Bible as we now know it) and developing creeds, the church became more focused in its understanding of the truth. However, in reaction, this brought about another heresy.

Montanism — Some Christians saw this movement into more strictly defined thought as a limiting of the Spirit. They wanted more "spontaneity'' and freedom to follow the Spirit's leading. Montanus (130‑180) claimed he was the human instrument of the Holy Spirit. With some followers he proclaimed Christ's return was at hand. They practiced extreme asceticism, celibacy and they abstained from meat. In time, the group became more extreme: they had revelations, visions, some fell into a state of frenzy and made strange sounds, some claimed they spoke with angels.

What could the church do about this? Very little. Montanus was orthodox ("right thinking") in his doctrine except for claiming to be the mouthpiece of the Holy Spirit. The only charge against him that could stick was that he threatened the established teachings of the church by claiming direct revelation of other truths.

Though Montanism was dealt with by the early church and disappeared as a movement, the ideas have come back into the church time and again, even until today. ("Toronto Blessing").

Conflicts over the Trinity — Although we accept the doctrine of the trinity without much question, it took three centuries for it to be hammered into its present shape. Various ideas were put forth, debated and rejected before the truth was fully understood, as much as that is possible. To show some of the difficulties, we will consider only two of the heresies: Monarchianism and Arianism.

Monarchianism — (mono-one + archo = rule) was an attempt to worship one God, not three. It was taught that this one God revealed himself in three modes: Father in the Old Testament, Son in the New Testament and Spirit since Pentecost. But this means that the "after Pentecost God" abandoned the Son mode for the Spirit mode; thus Jesus Christ cannot now be in heaven as the Mediator between God and man. This heresy was condemned by the church, but in condemning it, a warning was issued not to go to the other extreme and teach that there are three substances in the godhead who are separate from each other.

Arianism — Arius (c.300), a pastor from Alexandria in Egypt, taught that the Father was the chief God and the Son and Spirit were demi-gods. Jesus Christ was a creature of God, but not eternal and the Spirit was a power of God. Jesus showed us how to become good through the use of our free will. He is a moral example for humankind.

This was strongly opposed by Athanasius (320­-370), bishop of Alexandria. All his life long he opposed this error. The various emperors took sides in this struggle and depending what side they were on, Athanasius would be exiled or recalled. Finally, the church at council meetings at Nicea (325) and Constantinople (381) drafted creeds which rejected these errors. We still have these creeds as the Nicaean and Athanasian Creeds (although Athanasius did not write the latter). Constantinople spoke the final word on the position of Jesus Christ and the Holy Spirit within the trinity. From here on, this doctrine is settled, although it is still, from time to time, under attack.