I will admit I have not read the whole Quran, but what I have seen so far makes me think it is no different from the Old Testament. One of the main examples comes from
Ebon Musings:
Is lying ever acceptable?
Lying forbidden: Sura 2:42
"Confound not truth with falsehood, nor knowingly conceal the truth."
Lying condoned: Sura 66:1-2
"O Prophet! Why holdest thou to be forbidden that which Allah has made lawful to thee? Thou seekest to please thy consorts. But Allah is oft-forgiving, most merciful. Allah has already ordained for you (O men), the dissolution of your oaths (in some cases): and Allah is your protector, and He is full of knowledge and wisdom."
Commentary: In 2:42 Muslims are instructed not to lie, generally a wise precept. But sura 66 tells a different story, one that sheds a great deal of light on the self-serving nature of some of Muhammad's "revelations".
Muhammad had several wives, among them Hafsah and Ayshah. In the interests of fairness (fairness!!) a revolving schedule was established wherein his wives would take turns to be with him - each woman would get one day at a time. But one day Muhammad decided to violate this schedule; he slept with one of his wives, Mary, on a day that was supposed to be another woman's turn. Hafsah found out about this and threatened to tell Muhammad's apparent favorite, Ayshah. To prevent her from doing this, Muhammad promised he would not touch Mary again, but Hafsah told the other women anyway. According to tradition, the Prophet reacted by becoming angry and secluding himself, ignoring all his consorts except Mary for several weeks.
Fortunately, it was at this point that Allah, the infinite, all-powerful creator of the universe, decided to step in and resolve this domestic dispute. If the text is to be believed, he explicitly gave Muhammad permission to break his promise not to touch Mary (to lie, in other words), then threatened the prophet's other wives with hellfire and eternal torture if they did not repent and obey their husband.
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It is not only a contradiction, but shows that Muhammad used Allah as a pocket god. He could just threaten anyone with hell to get his way and say that Allah told him to say it.
Quath