St. Justin Martyr on the Stoics & the Seed of Reason [Logos Spermatikos]

 And those of the Stoic school—since, so far as their moral teaching went, they were admirable, as were also the poets in some particulars, on account of the seed of reason [the Logos] implanted in every race of men—were, we know, hated and put to death,—Heraclitus for instance, and, among those of our own time, Musonius and others. For, as we intimated, the devils have always effected, that all those who anyhow live a reasonable and earnest life, and shun vice, be hated. And it is nothing wonderful; if the devils are proved to cause those to be much worse hated who live not according to a part only of the word diffused [among men] but by the knowledge and contemplation of the whole Word, which is Christ. And they, having been shut up in eternal fire, shall suffer their just punishment and penalty. For if they are even now overthrown by men through the name of Jesus Christ, this is an intimation of the punishment in eternal fire which is to be inflicted on themselves and those who serve them. For thus did both all the prophets foretell, and our own teacher Jesus teach.*

Martyr, Justin. The Writings of Justin Martyr (Annotated) (p. 83). Logia. Kindle Edition. 

There are actually two very remarkable things about this passage: 

First, that he freely grants that every race of man has within it the Logos, and he specifically acknowledges the Stoics of the Hellenic world as possessing Logos. Obviously, we can now consider that various Eastern masters like Confucius and Lao-tzu are potential bearers of the Logos, and we can further imagine that the Buddha himself and various Indian and Sikh masters had something of the Logos. 

Second, and perhaps more amazingly and seldom discussed, we see that the devils hate all who live reasonably and earnestly, shunning vice. 

The devils themselves are actively working to drive men to hatred of those who have any nobility to them to live a life according to good reason, and it is these men who literally put to death even Stoics out of their own madness. 

St. Just Martyr doesn't just imply that those who live in the light of proper virtue and rationality can be open to salvation even if they could not know Christ, but that they will be persecuted by the devils just like Christ. 

It is the nature of the demonic to tear down goodness wherever and however it can, and to mobilize and empower men to take over institutions so as to inflict moral & spiritual damage on the righteous.