|Icon of the Resurrection of Our Lord|
Skeptics are quite fond of pointing out the similarities between Christianity and certain mystery cults of antiquity, in order to insinuate that the similarities are (somehow) evidence of Christianity being some sort of fraud or myth. But these similarities are often cherrypicked from a wide range of beliefs and cults, omitting all those which bear no resemblance, and focusing on anything that has even a superficial resemblance. The result is usually a drastic exaggeration of the actual parallels and overlap.
In addition, there is often a historical confusion over which direction the influence is running in. Many ancient religions and cults were influenced by the spread of Christianity, and adopted elements into themselves. Shoddy amateur scholarship that pollutes the internet is prone to see any similarity and falsely infer that the influence necessarily ran in the other direction, since paganism in general preceded Christianity.
With all that said, to the extent that there is some legitimate overlap between certain elements of Christian worship, piety, and devotion and that of certain pagan cults, this is hardly surprising and is no challenge to the truth of Christianity.
In the February 2013 issue of First Things, Orthodox theologian David Bentley Hart addresses this topic from this angle. Granting that there are more substantial similarities than some Christians usually feel comfortable admitting -- sacramental initiation rites which are supposed to conquer the power of death, for example -- Hart notes that it's a false inference from these facts to the story of Christ being false or somehow stolen from the pagan religions.
There was a brief period in the early heady days of anthropology of religion when James Frazer was still in fashion, during which it was regarded by many as something of a scandal that so many seemingly common elements could be found in both Christianity of the early centuries and many of the pagan devotions of late antiquity. To this day in fact, there are Christians who become terribly anxious at the suggestion that the early Church, in many places, had something of the form of an Asiatic or Hellenistic mystery cult, or that other sects that offered salvation with a savior deity cherished some of the same religious aspirations of Christianity.
Really, though, there is nothing alarming or even surprising in the discovery that the gospel spoke to religious hopes that existed outside its corporate boundaries, or that early Christian devotion should have been expressed in forms not wholly alien to the culture and language of its time.
On the contrary, we confess that Christ came "in the fullness of time" (Gal. 4:4), so it makes sense that his coming into the world would constitute the fulfillment of certain religious longings of the world which was, after all, created through Him. Longing such as as the desire to see the "face of God", as expressed -- among other places -- in Apuleius' The Golden Ass. Hart notes that these religious expectations are both fulfilled and overturned in Christ. The face of God is revealed, but it's revealed in a scandalous form: that of a crucified Jewish peasant.
My main interest in the discussion is to affirm that these two apologetic approaches are compatible, rather than mutually exclusive. Provided that the apologist is careful not to blithely dismiss all similarities while accurately articulating the great, significant divergence that does in fact occur with the advent of Christianity.
 - This article is behind a paywall. Hart has a similar piece from 2011 that is available for free here.