A reader asked me to discuss this topic. It is a wide subject, so here I will give just the basics.
Tertullian, in his Prescription Against Heretics, wrote:
Writing to the Colossians, he [Paul] says, “See that no one beguile you through philosophy and vain deceit, after the tradition of men, and contrary to the wisdom of the Holy Ghost.” He had been at Athens, and had in his interviews (with its philosophers) become acquainted with that human wisdom which pretends to know the truth, whilst it only corrupts it, and is itself divided into its own manifold heresies, by the variety of its mutually repugnant sects. What indeed has Athens to do with Jerusalem?What concord is there between the Academy and the Church? what between heretics and Christians? Our instruction comes from “the porch of Solomon,” who had himself taught that “the Lord should be sought in simplicity of heart.” Away with all attempts to produce a mottled Christianity of Stoic, Platonic, and dialectic composition!
That famous phrase “What indeed has Athens to do with Jerusalem” has roiled the waters of Christian controversy over the centuries, so many are often surprised to find in the narthex of some Eastern Orthodox churches the images of Greek philosophers and poets. True, they are not given halos, but there they stand, “Athens,” meaning Greek philosophy, within “Jerusalem” — meaning Christianity.
Even today the presence of the Greek philosophers in churches is a matter of controversy. In the Painter’s Manual of Dionysius of Fourna, we find the heading “Οι σοφοί των Ελλήνων όσοι είπον περί της ενσάρκου οικονομίας του Χριστού” — “The Wise Ones of the Greeks who spoke of the Incarnate Economy of Christ.” And then are listed the “Wise Ones of the Greeks” and how they are to be painted. So that is how the philosophers were slipped into the Church — through the misrepresentation that they “spoke of the Incarnate Economy of Christ.” “Economy” here means essentially the divine plan God supposedly had for humans through the incarnation. Because they were primarily didactic, the “Wise Ones” were rarely seen in icons, but are more widely found in wall paintings, etc. — images not intended for veneration.
But enough of that. Let’s take a look at how the “Wise Ones [Sophoi] of the Greeks” are depicted in Eastern Orthodox iconography. Here is how they appear in the depiction by the modern iconographer Vlasios Tsotsonis at the Great Meteoron or Transfiguration Monastery at Meteora, in central Greece. They are on an exterior wall on the south side of the refectory. Above them on both sides and leading to the central figure of Jesus are smaller images of Old Testament figures, so all together the Philosophers and Old Testament figures are considered foreshadowings of the coming of Jesus.
This is the left side of the door:

And this is the right side of the door:

And to give a better idea of their positioning, here is the central image of Jesus above the door. The Greek title inscription reads “This is the King of Glory.”

Now let’s look examine the images in greater detail. We will begin at the far left side:

At left is “The Greek Sibyl, Philosopher.” At right is “Solon, the Wise and Lawmaker.”
Then we have “The Greek Pythagoras, Philosopher and Mathematician” and to his right “The Greek Socrates, Philosopher.”

The next two are “The Greek Apollonius, Philosopher” and the non-philosopher “The Apostle to the Nations Paul, Martyr of the Church of Greece.”

Above them are Old Testament figures: “The Prophet Habakkuk,” “The Prophet David,” “The Prophet Elijah,” “The Prophet Jonah,” “The Prophet Zechariah,” and “The Patriarch Jacob.”
Moving to the right of the door, we see “Holy Justin the Philosopher and Martyr.” Beside him is “The Greek Homer the Poet.”

Then come “The Greek Thucydides the Historian” and “The Greek Aristotle the Philosopher.”

And finally, we see “The Greek Plato the Philosopher” and “The Greek Plutarch, the Father of History.”

Above them are figures from the Old Testament: “The Prophet Solomon,” “The Prophet Isaiah,” “The Judge Gideon,” “The Prophet Jeremiah,” “The Prophet Moses,” and “The Prophet Ezekiel.”
Just which “Philosophers” are included in such depictions vary from place to place, as do the texts on their scrolls. We can easily see that the list in the Painters’ Manual of Dionysius of Fourna differs somewhat from those depicted in the Great Meteoron. That former list consists of:
Apollonius, Solon, Thucidides, Plutarch, Plato, Aristotle, Philo, Sophocles, “Thoulis, King of Egypt,” “The Diviner Balaam,” and “The Sage Sybil.” The Sibyl — who was actually one of a number of Sybils — was a pre-Christian prophetess, who supposedly foretold the coming of Jesus. Thoulis is a completely fictional character said to have been an early Egyptian King who conquered the entire world and foretold the doctrine of the Trinity. He appears in a book written in the 500s c.e. — the Khronographia or “Chronicle,” by the Syrian John Malalas (c. 491 – 578).
Now as you can tell, there is much nonsense in this notion of pre-Christian figures somehow “foretelling” Christian events, but Eastern Orthodoxy has never been strong on facts but always prolific in imagination.
The “Wise Ones” are found in Bulgarian and Serbian Church art as well. In Russian Orthodoxy, the pre-Christian figures generally appear in the wall art of the 16th to 18th centuries after the impetus for their inclusion was given by material written in the 1500s — Пророчества еллинских мудрецов — Prorochestva ellinskikh mudretsov — “Prophecies of the Hellenic Wise Men.” It was a compilation of sayings attributed to philosophers, etc. — including forged sayings — given a rather strained Christian interpretation.