I'll give you that, Andrew. I hadn't looked into this subject before and was curious what others would make of the sources Pearse discusses. But as I look around a little more, I see that Irenaeus says some things about the Carpocratians in AH 1.25.4 that could include orgies and infanticide or at least have given others that impression (and he refers to their writings):
So unbridled is their madness, that they declare they have in their power all things which are irreligious and impious, and are at liberty to practise them; for they maintain that things are evil or good, simply in virtue of human opinion. They deem it necessary, therefore, that by means of transmigration from body to body, souls should have experience of every kind of life as well as every kind of action (unless, indeed, by a single incarnation, one may be able to prevent any need for others, by once for all, and with equal completeness, doing all those things which we dare not either speak or hear of, nay, which we must not even conceive in our thoughts, nor think credible, if any such thing is mooted among those persons who are our fellow citizens), in order that, as their writings express it, their souls, having made trial of every kind of life, may, at their departure, not be wanting in any particular. It is necessary to insist upon this, lest, on account of some one thing being still wanting to their deliverance, they should be compelled once more to become incarnate. They affirm that for this reason Jesus spoke the following parable:— “Whilst you are with your adversary in the way, give all diligence, that you may be delivered from him, lest he give you up to the judge, and the judge surrender you to the officer, and he cast you into prison. Verily, I say unto you, you shall not go out thence until you pay the very last farthing.” They also declare the “adversary” is one of those angels who are in the world, whom they call the Devil, maintaining that he was formed for this purpose, that he might lead those souls which have perished from the world to the Supreme Ruler. They describe him also as being chief among the makers of the world, and maintain that he delivers such souls [as have been mentioned] to another angel, who ministers to him, that he may shut them up in other bodies; for they declare that the body is “the prison.” Again, they interpret these expressions, “You shall not go out thence until you pay the very last farthing,” as meaning that no one can escape from the power of those angels who made the world, but that he must pass from body to body, until he has experience of every kind of action which can be practised in this world, and when nothing is longer wanting to him, then his liberated soul should soar upwards to that God who is above the angels, the makers of the world. In this way also all souls are saved, whether their own which, guarding against all delay, participate in all sorts of actions during one incarnation, or those, again, who, by passing from body to body, are set free, on fulfilling and accomplishing what is requisite in every form of life into which they are sent, so that at length they shall no longer be [shut up] in the body.
And while I figure it is referring to pagan practices, Barnabas 20 is at least addressed to Christians and warns against "murderers of children":
But the way of darkness is crooked, and full of cursing; for it is the way of eternal death with punishment, in which way are the things that destroy the soul, viz., idolatry, over-confidence, the arrogance of power, hypocrisy, double-heartedness, adultery, murder, rapine, haughtiness, transgression, deceit, malice, self-sufficiency, poisoning, magic, avarice, want of the fear of God. [In this way, too,] are those who persecute the good, those who hate truth, those who love falsehood, those who know not the reward of righteousness, those who cleave not to that which is good, those who attend not with just judgment to the widow and orphan, those who watch not to the fear of God, [but incline] to wickedness, from whom meekness and patience are far off; persons who love vanity, follow after a reward, pity not the needy, labour not in aid of him who is overcome with toil; who are prone to evil-speaking, who know not Him that made them, who are murderers of children, destroyers of the workmanship of God; who turn away him that is in want, who oppress the afflicted, who are advocates of the rich, who are unjust judges of the poor, and who are in every respect transgressors.
These are just some things from the second century CE I've stumbled upon and I'm curious what others here may make of them (and my apologies if anyone has already mentioned them).
I also found something in this book that I figure is referring to pagan critics but perhaps could be relevant:
And I think GDon mentioned Clement of Alexandria (who also refers to their writings).
Strom. 3.2.5 and 10:
But the followers of Carpocrates and Epiphanes think that wives should be common property. Through them the worst calumny has become current against the Christian name. This fellow Epiphanes, whose writings I have at hand, was a son of Carpocrates and his mother was named Alexandria ...
These then are the doctrines of the excellent Carpocratians. These, so they say, and certain other enthusiasts for the same wickednesses, gather together for feasts (I would not call their meeting an Agape), men and women together. After they have sated their appetites ("on repletion Cypris, the goddess of love, enters," as it is said), then they overturn the lamps and so extinguish the light that the shame of their adulterous "righteousness" is hidden, and they have intercourse where they will and with whom they will. After they have practiced community of use in this love-feast, they demand by daylight of whatever women they wish that they will be obedient to the law of Carpocrates-it would not be right to say the law of God. Such, I think, is the law that Carpocrates must have given for the copulations of dogs and pigs and goats. He seems to me to have misunderstood the saying of Plato in the Republic that the women of all are to be common. Plato means that the unmarried are common for those who wish to ask them, as also the theatre is open to the public for all who wish to see, but that when each one has chosen his wife, then the married woman is no longer common to all.