By the term “early Christians,” I am primarily referring to the Christians who lived in the first two centuries of Church history prior to the Council of Nicea and Roman Catholic apostasy. The Apostle John was still living at the beginning of this early period. The first generation of early Christians were men like Polycarp who had been personally discipled by one or more of the apostles. The period ended with a man who was only one human link removed from John—Irenaeus, a pupil of Polycarp. The term “early Christians” DOES NOT refer to beliefs and practices of anyone labeled as a heretic by that church. For more information on early Christian beliefs, I recommend David Bercot’s books Will the Real Heretics Please Stand Up, The Kingdom that Turned the World Upside Down and the Dictionary of Early Christian Beliefs available here.
Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear: For if God spared not the natural branches, take heed lest he also spare not thee. Romans 11:20-21
Be not seduced by strange doctrines nor by antiquated fables, which are profitless. For if even unto this day we live after the manner of Judaism, we avow that we have not received grace. Ignatius: to the Magnesians (A.D. 35-105) ch.7
It is monstrous to talk of Jesus Christ and to practice Judaism. For Christianity did not believe in Judaism, but Judaism in Christianity, wherein every tongue believed and was gathered together unto God. Ignatius: to the Magnesians (A.D. 35-105) ch.10
But if any one propound Judaism unto you, hear him not: for it is better to hear Christianity from a man who is circumcised than Judaism from one uncircumcised. Ignatius: to the Philadelphians (A.D. 35-105) ch.6
In the next place, I fancy that you are chiefly anxious to hear about their not practicing their religion in the same way as the Jews… For whereas the Greeks, by offering these things to senseless and deaf images, make an exhibition of stupidity, the Jews considering that they are presenting them to God, as if He were in need of them, ought in all reason to count it folly and not religious worship. Letter to Diognetus (A.D. 125-200) ch.3
That the Christians are right therefore in holding aloof from the common silliness and error of the Jews and from their excessive fussiness and pride, I consider that you have been sufficiently instructed; but as regards the mystery of their own religion, expect not that you canst be instructed by man. Letter to Diognetus (A.D. 125-200) ch. 4
“But if some, through weak-mindedness, wish to observe such institutions as were given by Moses, from which they expect some virtue, but which we believe were appointed by reason of the hardness of the people’s hearts, along with their hope in this Christ, and [wish to perform] the eternal and natural acts of righteousness and piety, yet choose to live with the Christians and the faithful, as I said before, not inducing them either to be circumcised like themselves, or to keep the Sabbath, or to observe any other such ceremonies, then I hold that we ought to join ourselves to such, and associate with them in all things as kinsmen and brethren. But if, Trypho,” I continued, “some of your race (the Jews), who say they believe in this Christ, compel those Gentiles who believe in this Christ to live in all respects according to the law given by Moses, or choose not to associate so intimately with them, I in like manner do not approve of them.” Justin Martyr (A.D. 160) Ante-Nicene Fathers vol.1 pg.218