I have a Hindu friend who wants to understand Islam. He wants to know why having sex with one’s girl friend is prohibited by Islam. Please answer this for me.
The basic reason for this prohibition is that Islam lays its social structure on the basis of a permanent relationship between a man and a woman in the form of a family. This relationship comes into existence in the form of an everlasting marriage bond. Consequently, to preserve this marital relationship, it forbids all forms of temporary associations between a man and a woman. Premarital sex or sex out of wedlock does not allow a family to come into being. It is because of this that sex before marriage has been prohibited.
However, you might need to communicate to your friend the reason why Islam stresses on the institution of family. For unless he understands this reason, he might not grasp fully the real reason of prohibition of sex out of wedlock. So, a brief explanation:
You see a person born in this world cannot traverse its rugged terrain all by himself. Throughout his lifetime, has to remain dependent on a number of relationships, and without these he cannot embark on this tempestuous voyage. In the prime of his youth, he might consider himself to be the king of the world but during his childhood and old age he needs the love and affection of the near ones which must not cease with time. In both these periods of life, he must be looked after by those who have warmth and compassion for him. In other words, his life demands relationships which should be permanent in nature so that his parents, children, brothers and sisters -- all can play their role in his life. Only the institution of family can ensure him these privileges. Without this institution, one may have an enjoyable youth but it is very likely that his childhood and old age will be spent in misery.
Similarly, it is evident that in contrast with almost all the animal forms, the relationship once formed between a man and woman has a permanent impression in human memory. In all animals, the relationship between a male and female species does not leave a lasting imprint in their minds. The male species departs from the female soon after mating, while the female, once she has brought up her young, resigns them to the whole world to start the cycle all over again. The affection it has for its young and the fondness for the male who fathers them is only temporary. With the passage of time, this attachment is obliterated from her mind. However, in case of human beings, this attachment is so strong that it is even felt at the level of grand and great grand parents. Reason demands that just as there is a permanent base in human memory regarding these relationships, the actual relationships also be permanent.