Warning: this Christianity- and Christmas-themed post may offend or disgust. The procedure described is unpleasant for the receiver.
Fertilisation of an egg cell requires sperm to reach it, which does not require breaking the hymen. A thin tube, such as a hollow straw or reed, can be inserted through the small opening in the hymen to pump sperm (obtained via male masturbation) into the vagina. The simplest way to pump the sperm is to suck it into the straw with one’s mouth and then blow it out. Another way is with an enema pump (bulb syringe) that can be constructed with primitive technology: a hollow leather ball glued to a reed using resin, tar or bone glue. The seams of the leather ball can be waterproofed with tar. The ball can be made to spring back into shape after squeezing, e.g. by constructing it with wire hoops or springs inside.
Successful fertilisation with the above method likely requires many attempts, because the probability of pregnancy from unprotected sex during the most fertile part of the menstrual cycle is 30%. Sexual activity causes hormonal changes in the female organism that facilitate fertilisation, which a simple reed insertion probably does not, but it may be possible to create similar hormonal changes with an erotic massage.
The above method can be used to arrange a virgin birth in a primitive society. No miracles are required, although a virgin giving birth may be marketed as miraculous.
Modern in vitro fertilisation technology of course expands the range of ways to engineer a virgin birth.
Priests in Ancient Egypt could predict eclipses and the floods of the Nile by observing the stars and the Moon and recording their previous positions when the events of interest happened. The rest was calculation, nothing magical. Ordinary people saw the priests looking at the stars and predicting events in the future, and thought that the stars magically told priests things and that the prediction ability extended to all future events (births, deaths, outcomes of battles). The priests encouraged this belief, because it gave them more power. This is one way astrology could have developed – by distorting and exaggerating the science of astronomy. Another way is via navigators telling the latitude of a ship using the stars or the sun. People would have thought that if heavenly bodies could tell a navigator his location on the open sea, then why not other secrets?
Engineers in Ancient Rome calculated the strength of bridges and aqueducts, and estimated the amount of material needed for these works. Ordinary people saw the engineers playing with numbers and predicting the amount of stones needed for a house or a fort. Numbers “magically” told engineers about the future, and ordinary people thought this prediction ability extended to all future events. Thus the belief in numerology could have been born.
When certain plants were discovered to have medicinal properties against certain diseases, then swindlers imitated doctors by claiming that other natural substances were powerful cures against whatever diseases. The charlatans and snake oil salesmen distorted and exaggerated medicine.
Doctors diagnosed diseases by physical examination before laboratory tests were invented. Thus a doctor could look at parts of a person’s body, tell what diseases the person had, and predict the symptoms that the person would experience in the future. Exaggerating this, palm readers claimed to predict a person’s future life course by looking at the skin of their palm.
In the 20th century, some medicines were discovered to be equally effective at somewhat lower doses than previously thought. Then homeopathy exaggerated this by claiming that medicines are effective when diluted so much that on average not a single molecule of the drug remains in the water given to the patient.
In all these cases, superstition only adds bias and noise to scientific results. Science does not know everything, but it is a sufficient statistic (https://en.wikipedia.org/wiki/Sufficient_statistic) for superstitious beliefs, in the sense that any true information contained in superstition is also contained in science. Nothing additional can be learned from superstition once the scientific results are known.
When a person says that some god wants X or rewards X and punishes Y, then how do they know? They, a limited human, claim knowledge of the mind of a god. When asked how they know, they say either that the god told them directly (using some revelation or sign perhaps) or that the god told some other person (a prophet) in the past, who passed on the message in the form of a book or an oral tradition. They certainly do not have replicable experimental evidence. If some other person was told, then recall the telephone game (children whispering in each other’s ear change the message radically) and people’s general lying, misunderstanding and misremembering. In any case, at some point a god must have told a person.
Let us look at this unavoidable transmission link between a purported god and a human. Could not an evil spirit have impersonated the god to the human (if evil spirits exist in their religion)? Or could it have been just a hallucination, dream, false memory? Psychology shows false memories are easy to induce (Brainerd and Reyna 2005 “The science of false memory”). How could a human tell the difference? Plenty of people in insane asylums claim not only to know a god’s will but also to be a god.
If there is a method for distinguishing real revelations from gods from false ones, how do you know it works? Either a god told you directly that it works or a person told you. In both cases we arrive at the previous question: how do you know it was a god and that you (or the other person) understood and remember the message correctly? If there is a method for finding and verifying good methods of distinguishing real from fake revelations, how do you know that works? And so on. Everything eventually relies on belief in the claim of a human. There is always a positive probability that the human imagined things that were not there or is deceiving self or others. Any religious claim is wrong with positive probability.
The next fallback position for advocates of religion is that even if it is wrong with positive probability, it does no harm to believe it. But how do they know? Back to the question about knowing the mind of a god. Why cannot a god reward nonbelievers and punish believers? And which religion out of the multitude in the world should one believe for maximal benefit? Some religions claim that a wrong religion is worse than none (heresy worse than paganism), some the opposite. To compare the expected benefit from believing different religions and from atheism, one needs to know the size of the rewards and punishments and also their probabilities. All this reduces to (conflicting) claims by humans about the will of a god. Which are wrong with positive probability.