5 strongest arguments against the Quran:
1) The quran
5) Common sense
Hope I helped.
So I thought I'd expand on the above, because I honestly meant these to be arguments.
1) The quran:
The quran claims itself to be the perfect uncorrupted word of god. That's it's biggest flaw. It invites challenge in a way other holy texts don't, and is really to arrogant for it's own good. The level is enough that it doesn't have the flexibility needed to stand the test of time. The fact that it doesn't have this flexibility, and that it needs it in the first place, is an argument against it in my opinion.
There's only so much a human being can reasonably be held accountable for when it comes to spiritual matters. There's a verse in the quran which says allah has not given us two hearts. I personally view this as metaphorical, not literal. We view and believe certain things a certain way. I cannot at the same time believe in the quran while seeing flaws in it.
The quran, like all the other holy texts, claims to be the word of god. The way to verify this is testing it, see if it stacks up. Quite frankly it doesn't. Dust devils and jinns, spontaneous human creation, great flood, there's a lot to choose from, but I'll pick a few.
The story of the arc and the great flood. This would have happened around 4000 years ago. It's quite simply impossible for the number of races, ethnicities and the huge amount of genetic traits to come from one incestuous family in just 4000 years. It cannot happen. Something else that puts a hole in the story is the amount of people who were thriving at this point. God flooded the entire world. Except for the Chinese who were developing at an incredible rate and remained unaffected from a global flood that wiped out every human on the planet. The Japanese were also unaffected. And the Africans. And the Europeans. And the Native Americans. And the Aztecs. And the South Americans. And most of the middle east. The flood never happened. It's not real.
The quran teaches that humans were created from clay in a specific creation. If you're to count on the hadiths, then it's just even more ludicrous. We know the first human was not a 90 foot tall clay giant. Even if you don't take the hadiths into account, it also doesn't account for evolution, the proof of which is overwhelming. Nor does it account for the number of people today who have Neanderthal DNA in them from before the Neanderthals went extinct. Everything I know to be proven fact contradicts the claims of the quran. The only logical conclusion I can come to is that it was a story told by ancient societies because they didn't have any answers. Adam never existed. It's not real.
The sun orbits the Earth...yeah, we've known that's bullshit for a few centuries now.
It says in the quran that in the embryo/foetus the bones are the first thing to form. "So we made the clot a morsel, so we made the morsel bones, so we clothed the bones (with) meat". This is wrong. The skeleton is actually among the last to be formed. You'd think the all knowing creator of everything would realise this. It's wrong.
The stars are missiles to be hurled at jinns. Or they hunt demons. I haven't read the quran in a while so I can't remember the exact quote, but you can look it up to see exactly what it says. This is also wrong. The stars are just stars, they do the exact same thing as the star we orbit, the sun.
Women are defective in intelligence. Coming from a culture where gender mixing is the norm and close relationships aren't looked down upon, I can tell you this isn't true from my own experience. And then there's current trends in school grades, sciences, IQ and employment performance, the fact there are women in MENSA (if you don't know MENSA is like a super genius club, only 2% of the human population globally have a high enough IQ to qualify for membership). Now we live in an age men and women have equal rights, women are on the same level and even starting to out preform men. So I'm going to say this is wrong.
Do you believe that allah puts a veil over our hearts? If the answer to this is yes, then my reply to that would be that I'm blameless. If the reason I don't see the truth of islam is because allah put a veil over my heart, then it stands to reason I'll be punished (by being sent to hell) for a crime I didn't commit. My reason for saying I'm being punished for a crime I didn't commit is that allah delibertly put a veil over my heart so I would never know him, therefore the fault is allah's, not mine.
Do you believe nothing happens accept by allah's will? If so then it's the same as above. If nothing happens except by allah's will, then allah made sure I wouldn't believe in him. So again the fault lies with allah, not myself.
Do you believe islam teaches there's no compulsion in religion? If so does that mean if you don't accept islam as true, then you go to hell? If so, this means that allah has told us something to be taken as truth, and he punishes us for taking him at his word instead of assuming he was lying.
Do you believe in the virgin birth? If so, can you understand why I might think it's more likely that a teenage girl told a lie rather than a virgin magically conceiving a child, carrying it to term, birthing it, and the child while still an infant speaking?
Can you also understand why it may be confusing that said infant would only speak once to a few people and refuse to speak again to others, which would cause all doubt in the divinity of allah to be wiped away?
Here's a situation. Let's say there's something in your house you don't like. It offends you. Let's also say you have the power of a god. Would you A) throw away the thing you didn't like or give it to charity, or B) bring it to life, give it intelligence so it can understand what's happening, enable it to feel pain, and torture it forever and ever and ever? Which is more merciful?
5) Common sense
It becomes a common sense issue. Let's say that I'm wrong. Let's say all the things I'm of the opinion are true are wrong. It doesn't change the fact that I find the quran unbelievable. I can't have more knowledge than what's available to me. Let's take evolution. I find it believable. I'm convinced of it. The quran goes against it. I have no reason whatsoever, nothing at all compelling me to believe the quranic story over proven scientific fact.
Or another, let's take the big bang. I'm convinced by what knowledge I have that before the universe, and after the universe, there was no Earth. This planet did not exist. It took a very long time for our star to be born and for our planet to form. This seems plausible to me. From what I know of physics and cosmology, I can accept this. I have no reason whatsoever to believe that the Earth existed from the start and was ripped apart from heaven.
Or another. The quran and hadiths suggest a flat Earth. At one point it's spread out like a carpet, at another the Earth is like an ostrich egg (had to pick the bird that buries it's egg and flattens the soil), allah will roll up the Earth like parchment/paper, and on and on it goes. Everything I'm aware of tells me this is wrong. It becomes less and less believable to me. So with all this in mind, common sense tells me that the only truth that lies hidden in the quran is simply the truths of the cultural norms and mindset of that society and time. Historically and psychologically it's interesting, but that's all it is. No more, no less.
And I have to admit, these aren't even my strongest arguments. I haven't thought about this endlessly, I haven't delved into the theology to throw things at you. The above is just what came to mind as I sit here filling the time on a lazy Sunday evening.