the christian rules about sex? why? , page-3

the following is one of many writings in the bible on the subject:

If a man takes a wife and, after sleeping with her.. did not find proof of her virginity and...the charge is true...she shall be brought to the door of her father’s house and there the men of her town shall stone her to death. She has done an outrageous thing in Israel by being promiscuous while still in her father’s house. You must purge the evil from among you. Deuteronomy 22

the above sounds quite harsh but i assume it is taken to be the word of your God.

putting aside, for a moment, the harshness of the penalty, could a white-Anglo-Saxon-Australian-Christian please explain to me what the rationale of your God would be for such a rule and why your God would consider the relevant behaviour to be 'evil'?

thanks