Summary:  Sometimes an Arabic Culture Defense is used to defend Muhammad's actions and sayings.  
1.  Culture and morality are two different logical categories.
2.  Thus, moral issues can be discussed independently of culture. 
3.  Consequently, the morality of Muhammad's actions and behavior may be appropriately discussed and evaluated. 

Frequently, non-Muslims are advised not to judge the traditions of Muhammad by Western cultural standards. On the surface, this seems like wise advice to follow. Muhammad lived a long time ago in an ancient Arabic culture that is quite foreign to us. Perhaps, it would be good manners to by-pass what seems antiquated, cruel, and perverse and to excuse it on cultural grounds.

However, this cultural defense of Muhammad seems to confuse moral values with cultural values. The word, culture, was derived from the Latin word, colere, meaning to cultivate or to bring from the ground. The development of human societies is dependent upon their physical environment. The Arabic Bedouins lived in tents and depended upon their camels for their nomadic movements across the desert. Their physical environment played a key role in determining the desert culture of the Bedouins. It influenced all aspects of their culture, such as, their food, clothes, travel, family structure, education, music, etc,.  In other parts of the world, the physical environment gave rise to other diverse cultures.  It is morally indifferent whether a person lives in a dwelling that is made of forest wood, animal skin, earthen adobe, stone blocks, Arctic ice, or plant fabric.  The mode of travel is not a moral issue.  There is no moral difference between a person who travels by automobile, airplane, camel, dog sled, Indian canoe, or horse.  Yet, these things provide cultural differences between people groups.

Moral values are distinct from cultural values. For example, lie telling is a moral value. It is considered virtuous when a person tells us the truth. Friendship is another positive moral value. These moral values were not cultivated from the ground, and they don’t come from our physical environment. Moral values find their ultimate source in Allah. Allah created human beings with a moral sense of right and wrong. Human beings have a conscience that indicates to each person a sense of good and evil. It is true that this ethical sense can become hardened and twisted, but even a hardened person tries to offer a positive moral justification for a bad deed. They might say, "The devil made me do it." "He had it coming." "I stole it because he had more than he needed."

Now, moral things, like friendship, are common to all of humanity. Everyone appreciates it when they are treated friendly and with respect. Honesty, courage, sacrifice, thriftiness, and kindness are other positive virtues that are universally respected. This does not mean that everyone exercises these moral virtues. In fact, human beings can, and often do, act contrary to what they know is right and good.

The fact that cultural values are different and distinct from moral values allows us to evaluate moral behavior. It makes it permissible, and even desirable, to have discussions on moral behavior observed in different cultures. For example, some ancient cultures sacrificed babies on altars. Morally, this is a depraved act, even though it was culturally acceptable. Now, if moral values were the same thing as cultural values, we would not have a basis to judge whether a society would be better without child sacrifice. There could be no moral progress in social behavior if cultural values were the same as moral values. If this were true, it would yield the absurd result that a baby-sacrificing culture would be morally equivalent to a non-baby-sacrificing culture.

So, to claim that no one has the right to judge the moral actions of Muhammad because he lived in an ancient Middle Eastern culture is mistaken. It shows that the person does not understand the difference between moral values and cultural values. Furthermore, this is a strange defense to make for Muhammad, because Muslims themselves make moral judgments regarding Western culture. However, if persons cannot make moral judgments about another culture, then Muslims have no right to make moral judgments about the behavior of non-Muslims.  But Muslims do make moral judgments about others. They argue that an Islamic culture would be morally better than any other culture.  So, it is hypocritical for a Muslim to object to a moral discussion of Muhammad's sayings and behavior on cultural grounds.

Culture itself is not the moral standard by which to determine whether or not an act is right or wrong. And thus, it is appropriate to discuss the moral worth of the sayings and actions of Muhammad. In conclusion, appealing to the norms of ancient Arabic culture to defend Muhammad's behavior is logically fallacious because it confuses the categories of culture and morality.