Unbelievers reject the virgin birth of Christ. Let's consider two theories they propose to account for why Matthew and Luke (allegedly) made up the story of the virgin birth:
i) It's a cover story to conceal a prenuptial scandal. Either Mary and Joseph had premarital sex or else she had premarital sex with someone other than her fiancé. The story of the virgin birth was fabricated to quell damaging rumors. Not only would such rumors sully her own reputation, but more importantly, sully the reputation of her son.
ii) It's just a variation on the conventional heathen motif about gods (or goddesses) who sire demigods by having sex with human mortals. Matthew and Luke adapted this motif to give Jesus instant exalted status.
Now, other issues aside, notice that these two theories are mutually contradictory. According to the first theory, the story of the virgin birth was invented to destigmatize Jesus. At that time and place, his out-of-wedlock conception and birth would tarnish his reputation. He could never live down the disgrace of his illegitimacy.
According to the second theory, the story of the virgin birth was invented to enhance his status. In Greco-Roman mythology, gods often had extramarital affairs, be it with virgins or married women. Children born of such unions were demigods. They enjoyed divine pedigree and superhuman abilities that made them heroes. They were a cut above ordinary mortals.
So these two theories pull in opposing directions. The first theory is based on Jewish social mores, where to be conceived out of wedlock, whether by premarital or extramarital sex, is shameful.
The second theory is based on pagan social mores, where to be conceived out of wedlock can be ennobling, even if that's due to an extramarital liaison, so long as one of the parents is a god (or goddess). That automatically confers both ascribed status (divine paternity) as well as achieved status (superhuman abilities) on the child. To put it bluntly, to be the bastard son of a god (or goddess) put you higher on the pecking order than to be the legitimate son of a human king. Bastard demigods outrank legitimate princes.
But, of course, that entire framework is ethically and theologically anathema to Judaism. So they can't both be right, although both can most certainly be wrong.