Over the past couple of hundred years, supposed-'parallels' between Christianity and paganism (or other religions) have often been pointed-out -- usually in an anti-Christian context such as trying to prove Christianity is not true; or not different from other religions (merely a derivative copy), or that Christianity is different but an inferior corruption of earlier patterns.
I mean such aspects (beloved of comparative religionists) as the birth to a virgin of the divine hero, the sacrifice of the divine hero (perhaps by something-like crucifixion), death and rebirth of a god... that kind of thing. In other words; similarities between Gospel accounts of the Jesus story on the one hand; and folklore, myth and other-religions on the other hand - parallels that are sometimes reasonably - but sometimes much less! - plausible.
Nowadays it strikes me that these alleged parallels and similarities to paganism etc. are always to those aspects of Christianity that I regard as either not being core Christian; or indeed tending to be anti-Christian and contradictory accretions to Christianity.
In other words, I feel that these may well be pagan survivals into Christianity. More exactly (I strongly suspect) the simple truth of Christianity was paganized from very early by those who 'inserted' the Christian message into a variety pre-existing pagan beliefs (just as an analogous process "Judaized" Christianty). These pagan framings ranged from the abstract and intellectually-complex 'omni-God' of the philosophers, to the 'primitive' and pagan idea of God as a tyrant-king who demands sacrifices as propitiation. (Sacrifice and propitiation were also a part of the Ancient Hebrew idea of God, as depicted in the Old Testament.)
Very unfortunately; mainstream Christianity was never cleansed of these alien and contradictory accretions - quite the opposite! They were often made into mandatory dogmas!
But the simple truth of Christianity - that those who follow Jesus may be resurrected to eternal life in Heaven - is absolutely unique to Christianity.
'Rebirth' is not resurrection! To attain eternal life via mortal-death is not the same as never-dying. To be resurrected into embodied form, and with our-selves preserved, is not the same as becoming eternal spirits, nor the same as living in an inert, unthinking and self-less bliss.
And the timeline of Christianity, with a start and end-point - beginning with Jesus, and achieving its objective with our post-mortal resurrection - is different from the timelessness and unchanging/ undifferentiated nature of abstract paganism; and from the cyclically repeating worlds of other religions.
And whether Jesus was born to a virgin, or died painfully by crucifixion, are not of the essence...
Maybe the lesson that modern Christians ought to have drawn from the attacks by comparative religionists and "anything but Christianity" neo-pagans, eclectics, and perennialists; should-have-been to set our house in order...
Christians can candidly acknowledged that mainstream Christianity, as well as various unorthodox and 'heretical' versions, have over the centuries included many pagan and Jewish elements, and these elements have, at times, dominated.
But Christians here-and-now can and should clarify, and expound, and make focal the simple essence of Christianity; and push to the edges (ignore, or make personal and voluntary) inessentials and the contradictory elements...
Because the supposedly-pagan aspects of Christianity are exactly the ones that - whatever the original reasons behind their association with Christianity, and whatever the reasons for their continued presence - don't fundamentally matter to the reality of Christianity: i.e. to what Jesus Christ offers us, personally, now.
Note added: I regard paganism as the spontaneous spirituality (not necessarily a religion) of ancient people and children. We (probably) all go through a phase of spontaneous paganism in our early life, whether or not that is overwritten by some other religion. But modern Man moves beyond spontaneous paganism; and while he may advocate neo-paganism and identify as a pagan - it cannot be a strong motivator, as evidence by the mainstream, or globalist-totalitarian, or merely self-gratifying, socio-political views of neo-pagans. This happens because the neo-pagan negative rejection of God's creation, is far more powerful than any positive spirituality - so de facto alliance with the dominant, worldwide, value-inverted Satanic leadership is highly likely.