Do keep in mind that Christians aren't going to be that impressed by similarity of imagery. Most are perfectly willing to acknowledge that Christian art grew naturally out of the pagan art of the time. You would need a very good argument as to why this indicates that an element of the Christian religion was plagiarized. For this reason, I wouldn't bother with the Horus thing.
Quite right. One common tactic when faced with similar motifs that clearly antedate Christ is to claim that demons, knowing what God intended, deliberately planted similar material in pagan myth
before the time of Jesus in order to discredit Christianity. Here's another excerpt from Justin Martyr's
First Apology, in which he states this doctrine:
CHAPTER LIV -- ORIGIN OF HEATHEN MYTHOLOGY.
. . . . The prophet Moses, then, was, as we have already said, older than all writers; and by him, as we have also said before, it was thus predicted: "There shall not fail a prince from Judah, nor a lawgiver from between his feet, until He come for whom it is reserved; and He shall be the desire of the Gentiles, binding His foal to the vine, washing His robe in the blood of the grape."
The devils, accordingly, when they heard these prophetic words, said that Bacchus was the son of Jupiter, and gave out that he was the discoverer of the vine, and they number wine among his mysteries; and they taught that, having been torn in pieces, he ascended into heaven. And because in the prophecy of Moses it had not been expressly intimated whether He who was to come was the Son of God, and whether He would, riding on the foal, remain on earth or ascend into heaven, and because the name of "foal" could mean either the foal of an ass or the foal of a horse, they, not knowing whether He who was foretold would bring the foal of an ass or of a horse as the sign of His coming, nor whether He was the Son of God, as we said above, or of man, gave out that Bellerophon, a man born of man, himself ascended to heaven on his horse Pegasus. And when they heard it said by the other prophet Isaiah, that He should be born of a virgin, and by His own means ascend into heaven, they pretended that Perseus was spoken of. And when they knew what was said, as has been cited above, in the prophecies written aforetime, "Strong as a giant to run his course," they said that Hercules was strong, and had journeyed over the whole earth. And when, again, they learned that it had been foretold that He should heal every sickness, and raise the dead, they produced Aesculapius.
In the twentieth century C.S. Lewis restated this doctrine in a kindlier manner. He said the reason there were earlier analogues of the Passion was that it was the one true myth. All the others were pale reflections that echoed back in time. he used the analogy of Plato's bed, i.e. that there was a perfect bed (along with everything else) in heaven, the quintessence of "bedness." Alll the beds on earth were imperfect copies. The earlier versions of the Passion / Resurrection myth were to introduce the human race to the concept.
While Lewis' version is less antagonistic to paganism than that of Justin Martyr, it is equally unfalsifiable and also turns cause and effect on its head.
