The Koran does talk about "nasara" in Arabic. Some authors think that the word designates CHRISTIANS, without any further details. Others, struck by the strange beliefs attributed to the "nasara" by the Koran, think that "NASARA" designates Jewish Christian sects, especially Ebionites, Gnostics, Nazarenes who - either coming ethnically from a Jewish extraction or "converted" to such sects (like Waraqah bin Nawfal according to Ibn Hisham).

In fact, the Koran seems to describe the "nasara" as :

1- holding both the Torah of Moses (Mussa) and the Injil of Issa (Gospel of Jesus

2-- believing only in "the Injil", the one and only Gospel, apparently the "Evangelium juxta Hebraeos"

3- of Hebrew or Aramaic Gospel attributed to Matthew,

4- by the Ebionites.

5- forbidding to eat pork; perhaps keeping also the sabbath, but probably circumcision.

6- denying the divinity of Christ (other times, both the Koran and the nasara seem to affirm it).

The Ebionites had both streams.

OTHER scholars say that those "nasara" were NON-Chalcedonian Christians like Jacobites, nestorians, monophysists - respectively denying the humanity of Christ, the two natures in Him .

The authors who think that the "NASARA" of the Koran designates more or less or/ and pseudo christian sects especially of Jewish origin and affiliation, believe that Christians children of the Church , in our Christian orthodoxy, are called "RUUM" ÉϘ ("byzantines") by the Koran.

It is risky to affirm categorically that "Islam" underwent the influence of this or that sect, however it seems likely that :

1- the Koran denied the divinity of Christ due to ebionite and arian influence.

2- the Koran confused between divinity and humanity of Christ due to the nestorian influence.

3- the Koran denied the crucifixion of Christ due to the gnostic docetes who claimed that Jesus had only the appearance of a body, cf. the apocryphal (or pseudepigraphic) Gospel of Peter.

4- the Koran criticized "Christians" for believing in three gods : Allah, Issa and Mary - perhaps due to the existence of a "marianistic" heresy.

Basic references about the various sects and heresies in the early Church : St. Iraeneus : "Adversus Haereses" St. Epiphanus, Bishop of Salamina (Cyprus) :"The Panarion" (All the schisms).

Fr. Louis Shikho , "The Nasara among pre-Islamic Arabs".