Acts of Apostles in the Early Church 

There are three primariy heresies of the early church: Ebionitism, Docetism, and Valentinism.

Ebionitism represents a general trend in the first and second centuries to interpret the identify of Jesus of Nazareth in ways inherited from Judaism. In essence, it says that Jesus was another prophet.

Little is known about the Ebionite movement. Even so, its beliefs are found today in contemporary Judaism. It is said by scholars to represent a Jewish way of thinking about Jesus.

This sect of Jewish Christianity became a problem, especially in relation to contentious issues such as circumcision, food laws, and observation of the Sabbath. Gentile Christians regarded themselves as liberated from ethnic, cultural and religious limitations, and cited Paul in support of their position.

Ebionitism has been rejected by the Christian church, because it doesn't do justice to the full significance of Jesus.

In the past hundred years, there has been a stream of conversions from Judiasm to Christianity. While some Jewish converts assimilated themselves to Christianity, abandoning their Jewish culture, others have seen themselves in a different way.

The term "Hebrew Christian" is now widely used to refer to a "Jew who has accepted  Christ as the Messiah and his savior, but who nonetheless chooses to retain his idenity as a Jew."

This Jewish identity is expressed in several ways, including observing Saturday as the Sabbath, but primarily by using the Hebrew term Yesua to refer to Jesus.

Docetism derives from the Greek verb dokein ("to appear"). The first person to have used the word "Doctism" in this sense was Serapion, bishop of Antioch.

The first explicit references to Docetism are found in letters of Ignatiusof Antioch in Syria, who was martyred at Rome.

Ignatius was concerned about two groups: the Judaizers, who wanted Christianity to remain within the orbit of Judaism; and the Docetists, who argued that the suffering of Jesus was illusory. 

Followers of Docetism refused to accept the fundamental humanity of Jesus of Nazareth.

Despite clear indications of the influence of Docetic ideas in the early church, it's difficult to find evidence of a coherent movement that could be called Docetism.

Some scholars have suggested the best way to define Docetism historically is to limit it to the belief that "Jesus was different from what he appared to be" (Norbert Brox).

Two types of Docetism can be identified, which are related but not identifical:

The first relates to Christ's incarnation (that Christ could not really be properly human, because there is no way the divine and human could coexist in a single being).

The second relates to his suffering on the cross (that even if Christ was indeed truly human, he didn't really suffer on the cross).

Valentinism is widely regarded as the original form of Gnostic Christianity. It is named after Velentinus, who apparently arrived in Rome about A.D. 135. He was born in the Nile Delta and was educated at Alexanderia.

The disciples of Valentinus claimed he was educated by Theudas, a pupil of Apostle Paul, from whom he derived his "secrety teachings." Also in Rome at this time was Justin Martyr, who condemned Valentinus' ideas, yet who took no official position within the Roman church.

Valentinism used the term "fullness" to refer to the dewlling place of the true God, the Father of the Universe, as well as a host of eternal beings who lived in perfect harmony with each other.

For Valentinism, Christ is the redemeer figure who awakens the divine spark within humanity, enabliing it to find a way back to its true home.

So why does the church reject Valentinism? Because it's seen as an attempt, in effect but not intention, to subvert the church from within.

Both Valentinism and members of the mainstream early church went to the same meetings, used the same vocabulary, read and respected the same scriptures, and took part in the same sacraments. The difference, however, lay in how all of these were interpreted.

__________________________________________________________________________

(Source: Addapted from "Heresy: A History of Defending the Truth", by Alister McGrath)