The existence of a traditional god is impossible - a god having the traditional traits described in holy texts of all of the world's larger religions.

The existence of such a god is impossible because patterns we can see in reality do not point to the existence of many, many of the traits it is commonly defined as having. I'll elaborate on the lack of signs of some of those specific traits below.

#1. Omnibenevolence: I would say that the sheer nature of reality necessitates that this cannot be a trait of any god that rules over our universe, unless it is not all powerful-or all-knowing. If it is not all-knowing or all-powerful though, then the ruler of the universe might be omnibenevolent though. Oftentimes people who believe in a god's omnibenevolence explain the unpleasant nature of reality by bringing up free will, or the fall of man from Eden, or God simply being able to define the nature of ethics.

So...first of all, regarding the free will argument, there are countless hardships people deal with that they have no control over. Smallpox, for example. While you could argue that human sloth led to smallpox being as big of a problem as it has been, because it wasn't cured earlier through the development of a vaccine...smallpox may have been around for thousands of years. I'd say it would be irrational to place that much blame on humanity...so I don't think it makes sense to say, "humanity should have just worked harder to invent vaccines for diseases that existed thousands of year ago...we should have researched more earlier." There are also numerous natural disasters, like earthquakes, and tornadoes, that are much more difficult to do anything to stop. In short, any ruler of the universe that is all-powerful and all-knowing has knowingly harmed humanity in ways that do not appear to be beneficial to humanity in any way, that humanity could have done nothing to alter.

Furthermore...having free will does not mean the ability to alter one's fate. Free will is the ability to roll different ideas around in one's mind and weigh one's option. This, in no way, means that anyone deserves anything except for eternal utopia...even the worst-behaving of us. The proper use of punishment is as negative feedback that discourages future harm to society or life forms, because regardless of how poorly we behave, one sentient beings pain or suffering really isn't that different from any other's. When you feel pain, I might as well be feeling pain too. It's pretty much the same thing...because either way a sentient being is feeling pain. You and I are basically the same person. There isn't really much difference between you living on and me dying, and me developing a major case of amnesia, but living on. Either way, a sentient mind is continuing to exist...and therefore, if Bob goes to eternal hell, that is punishment, rather than negative feedback, and so it might as well be a pointless form of harm to me, regardless of how poorly Bob behaved...and therefore any universe ruler who engage in such an act is either morally corrupt, not all-knowing, or not-all powerful.

Now, finally, some people say that God gets to determine ethics in God's universe. If that's the case...those ethics determined by God are not ethics. Ethics have to have something to do with assisting someone or something, or there is no reason to describe them as ethics. Just because an authority determines something does not make that authority's decisions about what is right or wrong any more universally binding than a next door neighbor's decisions about what is ethically sound.

So, any ruler of our universe must be either morally flawed, not all-knowing, or not all-powerful.

#2. Omniscience I've got a much shorter explanation regarding this trait. The ability to sense things without using one's natural senses just doesn't seem to exist in any way anyone can show. Now, if it did exist, that still wouldn't necessarily mean it exists in the universe-knowing, mind-reading sort of way it's typically said to exist in a traditional God. Furthermore, if it did exist in that kind of way, that still wouldn't necessarily mean that a being with more traits commonly attributed to God, such as omnipotence, exists with this type of omniscience as well. Some organisms have sixth senses, like the ability to sense heat or electrical signals. Nothing seem to be able to detect thought, or sense changes millions of miles away though...and I don't know how that "godly" brand of omniscience could come to exist in the first place, or why it would exist.

#3. Sentience existing outside of a physical body all examples of sentience that can be found exist within some kind of organic body...and the only way I can think of that it would exist in some other form would be through some sentient being with an organic body designing it. God is commonly defined as being both sentient and not having a single physical form.

Now...perhaps God could be a program in some computer program in which we all live. Such a program could allow God to have several of the traits commonly attributed to Gods, and they could simply be programmed into the God...no further laws of physics explaining how those traits could exist needed. The God could be omniscient, omnipotent, and have sentience outside of a physical body. However, even if such a computer program does exist, that doesn't mean such a God necessarily exists within it. Also, if this god does exist, I would say it would not be a traditional God, so much as a God designed by previous beings whose ancestors would have, at least at one time, been mortal and organic.

Now...hypothetically, a society could have developed the technological innovation to develop a computer program, or build entire universes, in which a god can rule eternally, inside which time work differently than outside these constructed universes...or perhaps such a civilization could have even built a god who has always existed. Perhaps this god is a caring paternal/maternal figure...just a not perfectly omni-benevolent one, or not all-powerful, or not all-knowing, and that's why the universe contains as much suffering as it does. Perhaps this God rules over an afterlife it created. In this way, a god could exist that is very similar to a traditional God...except for a trait or two that would remain impossible whether we live in a computer simulation or not.

#4. God's existence is impossible unless that God was designed by some other intelligent source...and so God's existence requires some type of previous designer.
I can't think of any way evolutionary processes, whether we're talking about organic evolutionary processes, or inorganic evolutionary processes like mineral evolution, could lead to the development of a God, and God having eternally existed, or sprung up from nothing, leads to many more questions than it answers. Claiming that God has always existed as an explanation for how such a being came to be is comparable to saying something like, "I've always had purple skin" as an explanation for how I developed purple skin."

Intelligent beings...humans...create extremely complex structures all the time that aren't developed in any other way...so that's the only path we have for the existence of a God - it must have been created by some other intelligence, if it exists.

Some people would respond to my statements with the question, "What about the universe itself? Doesn't it need an intelligent creator too, if a God needs one?" My response is...no...because patterns in reality show that, apparently, the universe doesn't need a creator because it doesn't seem to have one. There are no signs of intelligent design of this universe I'm aware of...so apparently, a lack of intelligence is capable of designing the sort of universe we see around us. A lack of intelligence does not, however, appear to be capable of designing the sorts of rare traits that a God would require to exist, because we don't see those traits in the universe yet.

From that point, a lot of people would make the claim that I'm biased. They'd look at things like, instead, "Well, if I begin with the assumption that a god did create the universe, then apparently intelligence does routinely design all the stuff you claim it does not design."

The problem with that outlook is that intelligence is more complicated than a lack of it...so given a complete lack of knowledge about any environment, it'd be safest to assume that intelligence does not exist. It's like...if you're about to enter into a room and you have the option of taking a guess that the room will be colored purple, or that the room might be any other color. You're probably safest guessing that the room will be any color besides purple. Intelligence would be comparable to the color purple, and a lack of intelligence comparable to any other color. A lack of intelligence appears to require less specific conditions than intelligence does...so it's more likely to be the source of something when we have no knowledge either way.

#5. Omnipotence and the ability to create matter from thought The laws of physics simply don't point to the existence of such powers, and if they did, that still wouldn't mean that they would exist in the ways needed to build universes or that gods have traditionally been described as using these powers...and if these powers did exist in that way, that wouldn't necessarily mean a god existed with other commonly described traits of gods to use these powers.

#6. Anything described as a miracle in a holy text typically involves breaking the laws of physics. Needless to say...if it breaks the laws of physics, it appears to be impossible.

A note regarding the meaning of "impossible"
Note that the meaning of the term "impossible" changes with the context in which it is used. Technically, nothing is impossible. Technically, the universe could have been hatched out of a chicken egg. However, in the same way that I will have no hesitation about claiming that it's impossible that the universe hatched out of a chicken egg, because I can think of no way that would occur, and no reason to believe it did, I will describe the existence of a traditional god with the traits I've described that God as having as impossible.

*My motivation for posting this

I am concerned that traditional God belief makes people less skilled at thinking about abstract concepts. I think God/god-belief, and the religious beliefs associated with it can have their benefits for society and individuals, but even in the best of instances, we're talking about a belief that I see as fictional, that gives people emotional rewards for having an untrue view of reality, and therefore, I'm concerned, rewards people for thinking less about the nature of reality.

Furthermore, there are other elements of God-belief, and the religious belief often associated with it, that I see as just harmful in themselves. Young earth creationism and the belief in hell for nonbelief are the two best examples I can think of. Hinduism may have encouraged the proliferation of the caste system. Viking religions may have encouraged people to more violent. The belief in an afterlife may make people less concerned about improving the world around them now...and while the belief in a watchful god may make people behave better, it may also cause them needless worry and inspire them to follow flawed systems of ethics that don't help anybody, out of fear of that god. The belief in the coming apocalypse may inspire people to care less about the long term future too.

Anything that gives people an inaccurate view of reality is going to give them disadvantages in at least some ways.

Now, again, some religious beliefs may make up for that through emotional or motivational benefits or communal atmosphere in churches. Therefore, I like the idea of developing replacements for those sorts of religious beliefs that don't involve inaccurate views of reality...so here's my proposed solution:

I'd like pantheism to spread. I'd like people not so much believing in an intelligent ruling deity, but rather having religions like Einstein had, or religions rooted in philosophy like much of Taoism and Buddhism - religions that can be held without having much of an opinion about the nature of any afterlife.

I'd like people to figure out what accurate perspective of reality is most fulfilling for them, and to try to perceive things that way. For example, Einstein said he wanted "to know God's thoughts - the rest are details." Einstein attempted to complete this goal through the study of physics, and in doing so, whether Einstein believed in an intelligent ruler of the universe or not didn't really matter. Either way, he'd be trying to piece together the clockwork of the universe to determine how it functions...and, presumably, his imagining of the universe as being created by a sentient presence inspired him, as personification often does.

Personally, I feel most inspired by imagining all life as sensory appendages of a single super organism...and from a very valid perspective that's what we are...but that's not the only valid perspective. You can view yourself as an individual, and your perspective can still be accurate. You are both a part of the super organism, and yourself - an individual.

What I'd love to see is a coming age of a mass blooming of new, very personal, pantheistic religions...with everybody having their own perspectives on what the nature of reality looks like. I'd like to see lots of people experimenting with ways to perceive reality that most inspire them.

Some people seem inspired by nihilism too...and I don't nihilism is a bad thing, necessarily. Society has rules that tend to bribe people into good behavior naturally. We're punished for crime. We lose friends for bad behavior and gain them for good behavior, etc, and our instincts tend to push us to have strong ties to whatever family group we create for oursleves.

Then there are Buddhist and Taoist brands of thought that tend focus on internal peace and flowing with the universe and whatnot (I think...I'm not an expert regarding those views).

Then...I think...eventually...there could come, perhaps, a type of pantheism inspired by Christianity rooted in selflessness and turning the other cheek and those sorts of Jesus teachings. Perhaps Jesus could be a sort of not actually godly, but a potential historical figure, and regardless of whether he existed or not, he'd represent those values.

LaVeyan Satanism, I think, might have some value. That's a code of conduct that encourage vengeance and carnality...and if gone about in the right ways, I'm
not sure that would necessarily be a bad thing. It'd certainly inspire people to seize
the day...and so long as the vengeance isn't taken to extremes, vengeance has
a way of discouraging future harmful behaviors. I disagree with this philosophy
more than many of the others personally...but I could see how it might be inspiring
to some people, and maybe even beneficial to society in general in some ways.

Some people really like nature. I know a guy who has a casual kind of view that trees
and rocks and elements of nature each have a spirit, and they're to be respected
like any living thing...and I could imagine this view being quite inspiring too, and
if literal beliefs are replaced with mere personification...this could be a perfectly accurate way of viewing reality.

So...there are countless ways to experiment with one's perspective on what reality looks like, while keeping that perspective perfectly accurate, and some of them can be deeply entertaining.