Justin does not say this. Always go to the sources! I have a selection online here:
tertullian.org/rpearse/mithras/literary_sources.htm
You can find Justin here:
tertullian.org/rpearse/mithras/literary_sources.htm#Justin Martyr
The passage from 1st Apology chapter 66 is the one in question, which says that the Mithraic ritual meal was a mockery of Christian communion.
Mithra is the ancient Persian god. He has no similarities with Christianity. He exists in Zoroastrianism, but very little is known about him. Zoroastrian literature only began to be written down in the 4th century AD, and exists only in medieval copies.
Mithras is the Roman god. He first appears in ancient literature around 80 AD, and in the archaology – we know most about him from archaeology – ca. 100 AD. Plutarch, writing around 110 AD, says that his cult was found among the Cilician pirates ca. 68 BC; but this is probably wrong, and a confusion with Mithra, because there is practically no archaeology for Mithras in Cilicia, and all of what there is is much later. The Romans called Mithras the “Persian god”.
Mithraic studies was created by the great Franz Cumont ca. 1894, who thought that Mithras and Mithra were the same, and that Mithras was the Roman version of Zoroastrianism. The archaeology shows that this is wrong; there are none of the distinctive underground temples of Mithras outside of the Roman empire, and the archaeology shows an origin in Rome in the first century AD, spreading out from there with the legions.
In 1971 at the conference of Mithraic studies it all came to a head, and various papers were read which more or less torpedoed Cumont’s idea. It’s dead and won’t come back (so Roger Beck, a modern Mithraic scholar). However speculation as to some link between the two continues, since the names are so similar. Probably there is something, but we don’t know what.
The Wikipedia article was deliberately poisoned by a gang of trolls back in 2011 (who drove off all the real contributors) to make it advocate the Cumont position. Much of what it says is deliberately misleading or untruthful.
My own site may help you.
tertullian.org/rpearse/mithras
Cranks like “Acharya S” profess that Mithras predates Christ, and that Christianity is borrowed from Mithras. No scholar thinks the latter. A handful of points of contact are exaggerated wildly to “prove” this. But as Manfred Clauss says in the standard undergraduate textbook, “The Roman cult of Mithras”, these similarities all arise from the common milieu of the ancient world. They don’t show borrowing in either direction.
In my own amateur opinion the statement of Justin says something about the cultists he knew in Rome in 150; it doesn’t give us general information.
All the best,
Roger Pearse
