I've extracted passages from Justin Martyr where he notes other Christian groups:
Justin Martyr,
First Apology:
http://www.earlychristianwritings.com/t ... ology.html
First Apology, Chap 26:
And there is Marcion, a man of Pontus, who is even at this day alive, and teaching his disciples to believe in some other god greater than the Creator. And he, by the aid of the devils, has caused many of every nation to speak blasphemies, and to deny that God is the maker of this universe, and to assert that some other being, greater than He, has done greater works. All who take their opinions from these men, are, as we before said, called Christians; just as also those who do not agree with the philosophers in their doctrines, have yet in common with them the name of philosophers given to them.
First Apology, Chap 58:
And, as we said before, the devils put forward Marcion of Pontus, who is even now teaching men to deny that God is the maker of all things in heaven and on earth, and that the Christ predicted by the prophets is His Son, and preaches another god besides the Creator of all, and likewise another son. And this man many have believed, as if he alone knew the truth, and laugh at us, though they have no proof of what they say, but are carried away irrationally as lambs by a wolf, and become the prey of atheistical doctrines, and of devils.
Justin Martyr,
Dialogue with Trypho:
http://www.earlychristianwritings.com/t ... rypho.html
Dialogue with Trypho, Chap 35:
And Trypho said, "I believe, however, that many of those who say that they confess Jesus, and are called Christians, eat meats offered to idols, and declare that they are by no means injured in consequence." And I replied, "The fact that there are such men confessing themselves to be Christians, and admitting the crucified Jesus to be both Lord and Christ, yet not teaching His doctrines...
There are, therefore, and there were many, my friends, who, coming forward in the name of Jesus, taught both to speak and act impious and blasphemous things; and these are called by us after the name of the men from whom each doctrine and opinion had its origin. (For some in one way, others in another, teach to blaspheme the Maker of all things, and Christ, who was foretold by Him as coming, and the God of Abraham, and of Isaac, and of Jacob, with whom we have nothing in common, since we know them to be atheists, impious, unrighteous, and sinful, and confessors of Jesus in name only, instead of worshippers of Him. Yet they style themselves Christians, just as certain among the Gentiles inscribe the name of God upon the works of their own hands, and partake in nefarious and impious rites.) Some are called Marcians, and some Valentinians, and some Basilidians, and some Saturnilians, and others by other names; each called after the originator of the individual opinion, just as each one of those who consider themselves philosophers, as I said before, thinks he must bear the name of the philosophy which he follows, from the name of the father of the particular doctrine.
Dialogue with Trypho, Chap 48:
But since I have certainly proved that this man is the Christ of God, whoever He be, even if I do not prove that He pre-existed, and submitted to be born a man of like passions with us, having a body, according to the Father's will; in this last matter alone is it just to say that I have erred, and not to deny that He is the Christ, though it should appear that He was born man of men, and[nothing more] is proved[than this], that He has become Christ by election. For there are some, my friends," I said, "of our race, who admit that He is Christ, while holding Him to be man of men; with whom I do not agree, nor would I, even though most of those who have[now] the same opinions as myself should say so
Dialogue with Trypho, Chap 80:
I admitted to you formerly, that I and many others are of this opinion, and[believe] that such will take place, as you assuredly are aware; but, on the other hand, I signified to you that many who belong to the pure and pious faith, and are true Christians, think otherwise. Moreover, I pointed out to you that some who are called Christians, but are godless, impious heretics, teach doctrines that are in every way blasphemous, atheistical, and foolish....
For I choose to follow not men or men's doctrines, but God and the doctrines[delivered] by Him. For if you have fallen in with some who are called Christians, but who do not admit this[truth], and venture to blaspheme the God of Abraham, and the God of Isaac, and the God of Jacob; who say there is no resurrection of the dead, and that their souls, when they die, are taken to heaven; do not imagine that they are Christians, even as one, if he would rightly consider it, would not admit that the Sadducees, or similar sects of Genist , Meristae, Gelilaeans, Hellenists, Pharisees, Baptists, are Jews (do not hear me impatiently when I tell you what I think), but are[only] called Jews and children of Abraham, worshipping God with the lips, as God Himself declared, but the heart was far from Him. But I and others, who are right-minded Christians on all points, are assured that there will be a resurrection of the dead, and a thousand years in Jerusalem, which will then be built, adorned, and enlarged, the prophets Ezekiel and Isaiah and others declare.