I came across this answer at Quora to the question what it is that make Islam so stupid. This answer really captures my views on the topic. It’s written by Gordon Stanger, a retired Chief Technical Advisor.
‘Stupid’ is a rather insulting term for the 1.6 billion people who believe in Islam, albeit most of them with only a superficial understanding. I think it is appropriate to respect their beliefs, without agreeing with them. Specifically, one could make a very strong case that Muslims are misguided, based upon at least the following:
Mohammed’s personal character was not that of a prophet of God. In particular, his sexual conduct was disgraceful – even according to Islam’s own records.
Mohammed was aggressive, supremacist and intolerant of all other beliefs. He made no attempt to differentiate between Biblical truth and falsehood, and was himself deluded in his dictated writings.
Mohammed was guilty of murder, incest, pedophilia, and many other sins.
Mohammed undertook no miracles, nor fulfilled any prophesies to validate his position as prophet. Islam’s attempts to argue to the contrary all fail when examined carefully.
Mohammed’s theological understanding was weak and shallow, being wrongly based upon a number of pre-Islamic pagan beliefs extant in his part of the world.
Many aspects of the Kabbah and Hajj are downright pagan in their origin.
The Qur’an is inconsistent, incoherent and historically incorrect, particularly in respect of Biblical misunderstanding and extra-Biblical invention.
Contrary to popular belief, there is no single definitive version of the Quran. There were originally many fragmented versions. Most of them were subsequently burned to yield the illusion of a single definitive text.
The Qur’an is misogynistic in the extreme, and condones numerous moral outrages.
Qur’anic apologists try to argue for the ‘scientific accuracy’ of the Qur’an. These arguments, when examined carefully, span the complete spectrum from facile, through preposterous, to the absurd.
Despite protestations to the contrary, Islam’s 1400+ years is a long history of violence, contempt, murder and religious intolerance, that continues to this day.
Islam has no remedy for humanities core spiritual problem – our tendency to sin.
And many more such arguments exist. Unfortunately, they have devised a system of intellectual and cultural linkage to Islam which prevents them from taking a dispassionate reasoned look at their own religion. Many of the very few who do value truth above peer-pressure have a hard time reconciling Islam with reality. Some even have to abandon Islam – but it’s a tough call. We should be understanding and supportive, not insulting.