This will perhaps be too brutal for some people but I will be straight forward. Since for me the question of God was always just simplistic and even unimaginative answer to the hard questions.
One of the fundamental problems is that people have a wrong picture of "nothing" and unability to think outside of passage of time. Most people see 0 as simply 0 while in fact 0 can be summation of -1 and 1 (or - and 27) and therefore if you at the same time create universe and anti universe you basically got something out of nothing. However the problem is that if God created universe then who created God ? You can say that god is "perfect" and doesn't need a creator but then you can say the same about the universe. Especially if time was created in the big bang and therefore asking what was before big bang is pretty much like asking what is northern of North pole.
However there is a whole array of arguments that cause serious doubt if this reality is created by the God people believe in.
1. Nuclear energy - if religions are correct God loves us and wish as well. However it remains very unclear why would he build in the concept of nuclear energy and atoms deeply into the reality, especially since this allows individuals to wipe out whole populations of humans, plants and animals. What means that God is either not fully good, he isn't almighty or it doesn't exist.
2. When a person takes a look at how this reality looks like it becomes very questionable if the purpose of this reality is life.
The thing is that surface of planet Earth is one very special place, because 99,999% of this reality is actually radioactive vacuum that has temperature hundreds of degress bellow freezing point. Not to mention that our solar system is full of dangerous asteroids and comets, barren empty worlds where nothing seems to live and our main source of energy is nuclear (Sun). Therefore it causes skin cancer if you are not careful, plus it messes with electronic equipment through it's activity. Also the distances that are between star systems are so large that even the closest star is hundereds of thousands of years worth of travel away, if you go with modern technology. Extra problematic factor is that Oort cloud of debris is around our solar system and even if we ever develope faster transporation the odds are that any ships will crash with comets and debris of the Oort coud, what can cause destruction of the ship. Just a few light days away from the Sun the conditions are pretty much "eternal darkness". Therefore if you just fly at 1% of speed of light you go at about 3 000 kilometers in second and you will need about 430 years to the nearest star with constant speed. However imagine what will happen if you hit just a rock or comet the size of an apple at this speed. What is extra problematic because tracking so small objects at that speed could be mission impossible. Hundereds of years of travel and avoiding apples in complete but radioactive darkness at 3000 km/s isn't a trivial task.
3. When you take a look at wider picture things become even more radical: since it is questionable what will be of this universe once stars spend their energy. Not to mention that there are very dangerous objects out there: from black holes that can destroy star systems to neutron stars that when collide with each other and therefore they can irradiate objects very far even by the scale of the universe. Plus since universe is chemically homgenous there could be hostile civilizations out there. So the bottom line is that reality at grand scale looks more like rat maze made by evil genius than a product of a loving God.
4. Soul - So far there wasn't a single concrete observation that such a thing exist while advances in understanding the chemo-physical dynamic of the brain are advancing on a daily basis. The biggest problem with soul is where souls were before we were born, since everyone that is alive right now was technically dead 200 years ago and they did not exist. In other words there doesn't seem to be any memory of life before birth.
5. Hell and Heaven - also unproven however the biggest problem is that such concepts have a number of serious logical problems. How can you enjoy in Heaven if for some reason happens that your mother, husband or child ended up in Hell due to some bad life circumstances ? Not to mention that eternal life is perfectly pointless because it can't have a goal ... since it will never end. Also after few billion years the whole thing will probably be a existential torture regardless of where you ended. In a way Hell is perhaps even better since it at least allows you dreaming of places where grass is greener.
6. I am from the place that doesn't have nice history and when I remember all those religious people killed during the war in my childhood as well as leveled churches that somehow doesn't fit into the reality with God. The thing is that innocent got slaughter and most of their killers aren't even presecuted or they were simply released despite evidences. Not to mention all those priests that were tortured, poisoned and killed by the communist regime, plus mass rape of nuns and ordinary women. Somehow all of that doesn't fit into the God story in my opinion.
7. Free will - if one acknowledges the rule/observation of determinism free will is just an illusion since every event is defined by it's past. What makes our reality a chain reaction rather than something were real decisions are made. What means that good and evil can't exist since everything is predetermined.
8. Every day there are thousands of commerical airplane flights as well as hundereds of satellites above as and there are no signs of the great father that lives on the clouds.
9. There are trully many religions and cults: in my opinion this is a big thing since it shows how religion is chaotic in a same way as human nature. Different people believe in mutually exclusive things and all of them can't be correct at the same time. If religious story were true a man would expect that there would be one or a few large groups, however since there are no concrete evidences people wander off into all kinds of things. (and no one seems to counter the trend)
10. Once you accept that physical evidences show much more evidences of evolution than creation it becomes evident that what we are watching right now is just a snapshot. In other words evolution isn't over and for 20 000 years humans will look differently than today, even if we skip the whole thing that involves genetic modifications, robots, cyborgs etc. As a matter of fact races are the start of divergent evolution that will take various human populations in different directions on the long run (each adepting to their environment). Actually the story of Adam and Eve is quite fishy if we consider that we have all those races on the planet, plus on the very long run the changes will be so large that our far ascendants wouldn't even look like humans. Especially if they will live somewhere in space for millions of generation that are yet to come. However the odds are that far future will belong to the machines since they are by definition more adaptable to the harsh, cold and radioactive reality that is our universe, especially since they can multiply much faster than organic life.
I have no doubts that there is emotional need for God(s) but the thing is that more careful observations of the reality are in direct conflict with what religions propagate.
I guess because a man is connected in peoples minds with strength, respect and for some reason dignity. Gives him a better position to enforce his commandments. Could have mentioned in the bible why he has a male name though.
