St. Epiphanius (367-404) in his Panarion admits that the earliest followers of Jesus were called Jessaens, that is Essenes, and Nazarenes, both of which groups were vegetarians, though he scornfully treats the contents of the  Ebionite Gospel, which portray Jesus and his followers as vegetarians who denounce the animal sacrifices, and who say that the scriptures sanctioning animal sacrifices in the Pentateuch are false scriptures.  Epiphanius contradicts himself even further by allying the Essenes and Nazarenes with the vegetarian Therapeutae of Alexandria.

    Nonetheless, in spite of Epiphanius' impossible goal of trying to ignore the fact that the Essenes and Nazarenes were vegetarians, still we are indebted to him, because it is in his Panarion that we have the most elaborate description of the Ebionites prior to the 1870 publication of the Gospel of the Nazirenes, which qualifies as being a copy of the Ebionite Gospel since it contains those passages quoted by early Church fathers who viewed the Gospel.
 
   The unbiased reader of the New Testament can see that vegetarianism underlies Jesus' cleansing of the temple, that his mission in "Epistle to the Hebrews," even as we have it, is clearly to abolish the animal sacrifices. Moreover, had Jesus really taught  "all foods are clean," it would have been nonsensical for him consistently to quote vegetarian Jews such as Ezekiel, Isaias, Jeremiah, Zechariah, Joel, Amos, and Habaccuc.  It would be the equivalent of Burger King or MacDonalds quoting Peta, Michael Klapper, Keith Akers, or John Robbins in order to justify eating flesh.

    In the Panarion the Ebionite Jesus and his hand-picked apostles and disciples are all described as not regarding the Pentateuch as sacred.  And Epiphanius describes a work, the "Ascents of James," by James, the brother of Jesus. In that work James sees Paul as an enemy of the truth, an apostate.  To the objective reader, it is not really strange at all to see Paul as an Apostate, for Paul, the pillar of Christian orthodoxy, affirms the validity of slavery, elitist societies of rich and poor, male chauvinism, bigotry towards homosexuals, and carnivorism.

   The values, or lack of them, really, in the Pauline epistles, were used by the bishops chosen by Constantine to turn away from the original teachings of Jesus. Whereas Jesus taught vegetarianism, the abolition of the animal sacrifices, and egalitarianism, "love your neighbor as your self," and "I have come to free the captive," Paul and the bishops of Constantine condoned slavery and elitist resentment-breeding societies of rich and poor.  The Essenes, Ebionites, and a number of writings by early church fathers such as Justin Martyr blatantly denounced the carnivorism that is sanctioned in the perverted version of Jesus' teachings that exists in Paul's epistles. So too, though Tertullian and Origen seem to honor Paul's work, nonetheless they both clearly see the animal sacrifices as demonic.

   Most readers are aware that the Essenes were vegetarians, but there is some confusion among many current readers as to whether the Nazarenes were. However, we have more than adequate documentation for the vegetarianism of the Nazarenes as well. For example, appended to the Clementine Recognitions is a profession of faith to Pauline Christianity which refers to the Nazarenes as  unequivocally vegetarian as well.

"I anathematize the Nazareans, the stubborn ones, who deny that the law of sacrifices was given by Moses, who abstain from eating living things, and who never offer sacrifice. I anathematize the Osseans, the blindest of all men who use other scriptures than the Law."

 From p. 54, The Essene Odyssey by Hugh Schonfield, Element Books, Ltd. Longmead, Shaftesbury, Dorset, 1984. P. 87.    Quoted from page 398, The Conflict of the Church and Synagogue, by James Parkes, London: The Soncino Press, Five Gower Street, 1934.
 

"When these things come to pass in Israel according to all the appointed times for the Institution of the Spirit of holiness founded in accordance with eternal Truth, they shall expiate guilty rebellion and sinful infidelity and procure Loving-kindness upon earth without the flesh of burnt offering and the fat of sacrifice, but the offering of the lips in accordance with the law shall be as an agreeable odour of righteousness, and perfection of way shall be as the voluntary gift of a delectable oblation."  "Prologue, Scroll of the Rule."   Essene Writings from Qumran, A. Dupont-Sommer, Meridian Books, World Publishing Company, 1962.

    It could hardly be more clear: both the Essenes and Nazarenes were vegetarians, but since the orthodox Jews and the Romans derived great profit from sacrificing animals and selling their flesh to eat, it was necessary to change the truth in order to continue making profits. So the scriptures were rewritten in order to make it appear that Jesus taught that "all foods are clean."
But there's plenty of evidences, historical as well as scriptural, that demonstrate the real beliefs of the original vegetarian and communal Christians.