Why does Islam prohibit pork?
Islam is not the only religion that prohibits pork. Judaism forbids its followers from eating pig meat and today both orthodox and conservative Jews who follow a kosher diet adhere to this and other dietary injunctions. Even though the prohibition of pork was lifted by Paul, this does not seem to be have been the desire of Jesus who said that he came to complete the message of the Torah and not to abrogate it. Eastern religions likewise proscribe the consumption of pig meat as part of a general prohibition against meat. Pig meat has been viewed by many religions as unclean.
Islam's prohibition is nothing more than following in line with previous religious traditions. The Quran explicitly mentions the prohibition of pork four times. Other than being a religious injunction, there is much scientific evidence proving that pork is not healthy for human consumption. The Quranic verses prohibiting pork also prohibit the consumption of blood and carrion and the meat of animals that have not been slaughtered according to Islamic precepts. It has been scientifically established that the meat of animals that have not been slaughtered according to Islamic precepts and the blood of animals contain microbes and bacteria that are harmful and these same microbes and bacteria are found in pig meat. This is the reason why the three have been listed together. However, it is not the scientific proof that legitimizes the prohibition. The Islamic position is that these are divine prohibitions and they are to be followed regardless of our understanding of them.
And God the Almighty knows best.