It's not attitude. 98% of them are strangers. I come from a conservative country where a woman who doesn't wear stole properly is considered immoral. That's what you get in Islamic countries, although other faiths also influence people in the same manner.
A concubine is a mistress. Be it Islamic or non-Islamic a concubine has a lower status than that of a girlfriend, fiancé or wife. Why should God/Islam support such a mean rule? God could just forbid it and punish those who practise concubinage. That will prevent many if not all Muslims from doing it. God is so sensitive about anyone not worshipping Him and He can't stop slavery and slave concubinage? Yes I mention slaves because you forcefully capture people and buy and sell them, when they are slaves. If a group of people harm you retaliate against them. Why imprison their family members and seize their wealth? I know that this rule is not followed by any war participant, but isn't Islam supposed to be fair and merciful?
I am talking about the definition of concubine from Bible. It has nothing to do with slavery. This was common among the Jews of Medina where the verses about concubines came. In Arabic its considered urfi marriage. Its a legitimate form of a relationship however its risky for a women since it can be denied by the man in case a pregnancy happens. Its a practice common among the poor or marriages between different tribes. The Biblical traditions separates this form of marriage from other forms of marriage. In fact most marriages today around the world are concubinage marriages.
In Judaism[edit]
In Judaism, concubines are referred to by the Hebrew term pillegesh. The term is a non-Hebrew, non-Semitic loanword derived from the Greek word, pallakis, Greek παλλακίς,[29][30][31] meaning "a mistress staying in house".
According to the Babylonian Talmud,[7] the difference between a concubine and a full wife was that the latter received a marriage contract (Hebrew: ketubbah) and her marriage (nissu'in) was preceded by a formal betrothal (erusin). Neither was the case for a concubine. One opinion in the Jerusalem Talmud argues that the concubine should also receive a marriage contract, but without a clause specifying a divorce settlement.[7]
Certain Jewish thinkers, such as Maimonides, believed that concubines were strictly reserved for kings, and thus that a commoner may not have a concubine. Indeed, such thinkers argued that commoners may not engage in any type of sexual relations outside of a marriage.
Maimonides was not the first Jewish thinker to criticise concubinage. For example, Leviticus Rabbah severely condemns the custom.[32] Other Jewish thinkers, such as Nahmanides, Samuel ben Uri Shraga Phoebus, and Jacob Emden, strongly objected to the idea that concubines should be forbidden.
In the Hebrew of the contemporary State of Israel, the word pillegesh is often used as the equivalent of the English word mistress—i.e., the female partner in extramarital relations—regardless of legal recognition. Attempts have been initiated to popularise pillegesh as a form of premarital, non-marital or extramarital relationship (which, according to the perspective of the enacting person(s), is permitted by Jewish law).[33][34][35]
http://en.wikipedia.org/wiki/Concubinage#In_JudaismIn the Quran only two options are given for prisoners of war. Freedom or ransom. The Quran considers taking care of prisoners of war as an act of charity also.