I apologize for taking so long to reply. I've read your post several times and have not been sure that I grasp all that you are saying. I'm just going to jump in anyway, and maybe it will become more clear.
From my point of view, it does not seem that my position is invalid but that the God concepts I have been invited to entertain appear invalid. They are either too small (for want of a better word) in that they are based upon human or physical nature tweaked in some fashion, or unfalsifiable. If we are not defining God in terms of our universe and ourselves and producing something that is ultimately not-God, then we run up against a God that we simply cannot define, imagine, exchange information with, or falsify (to name a few things we cannot do). So, it seems the problem is not with me. I have simply recognized the problem.
But, as I say, I may be missing your point.
If you believe that there is a definition or description of God that is falsifiable, then what is it and why is that which it defines or describes God vs not-God?
Well, you do bring up some good points and I believe my last response did have some errors in it. Nonetheless, I still think your point of view is wrong, so please allow me to explain.
From your point of view (so far as I understand it that is, please correct me if I'm wrong), God is the product of our own imagining. We try to imagine a God to "solve our problems" (or whatever other reason), and thus He bears our image. He mirrors us, so to speak. Your view actually is falsifiable (I wrongly claimed the opposite in my last post), in order to falsify it, we must discover some trait in God that we as humans don't have (I will address this further down).
My point of view, puts God first. We are God's creation, therefore we bear His image (thus we are His mirror, to some extent). As it turns out, my view does indeed appear to be non-falsifiable. As God is infinite, He bears more traits than we do. Thus, any trait that we find in ourselves, we will automatically find in God. If God does not exists I would be unable to prove it because my own view prevents my from attributing anything to God that I don't have. Such an attempt is impossible. Nevertheless, I do not abandon my view. Why? Because non-falsifiability is not a necessity for truth. It is necessary for good science, but that is the only place where it is necessary. For instance, my own existence is non-falsifiable to me. I can't prove that I don't exist. If I cease to exist, I also cease to comprehend anything, thus I would never realize that I didn't exist. Does that mean that I really don't exist? Of course not! "I think, therefore I am!"
So, while you can't prove me wrong, I can try to provide evidence which may prove you wrong. However, I have never really tried this before so may not do that well. Still, I hope you will humor me while I try to do so and hopefully we can both learn from this. I will make several arguments below and you are more than welcome to comment on them as you see fit. Note, however, that I am writing in the understanding that you were once a Christian, therefore some things will be assumed that you understand them (if you don't please indicate so in order that I may clarify), and once believed them. Thus, you may find that some of my arguments are an attempt to prove not so much your present position as false, but that your transition from belief to disbelief was flawed. I may not succeed in any of these attempts, but I'm still going to try because I still believe that this is the truth. Okay, here we go; and one final note, these are not in any particular order.
1: Complexity. It is clear from the Christian perspective of God that He is far more complex a being than we are. While we bear a limited number of traits, he bears an unlimited (i.e. infinite) number of them. It is thus very easy to imagine Him creating a being that is less in complexity. On the other hand, your view makes this impossible. A finite being cannot project infinite qualities onto another being. Why then do we have a concept of the infinite? How is it that we can conceive of the impossible? Granted, we cannot fully picture such a concept in our minds, but most everyone knows what "infinity" means. Besides, as finite beings, it is logical to conclude that we would not understand something that we are not. Likewise, it is logical that we cannot fully comprehend God because we are not God. Nonetheless, even little children understand the basic concept of God. In fact, studies have been done that indicate a natural tendency to believe in God. How could this be a normal natural thing to do if God does not exists? In any case, if God has but one trait that we don't have, then I believe it is safe to assume that we were made in God's image, not vice-versa. Thus, despite the inherent weakness of this argument (so far as I see it), it does help support a couple others below.
2: Mistakes. "To err is to be human." I don't quite remember where I heard that before, but I'm willing to gamble that either you've heard of it or at least you understand (and most likely agree with) what's being said. We make mistakes; it's as simple as that. Nobody is perfect and I dare say those who disagree only prove the point. That said, from your perspective, how can we successfully attribute perfection to God? The Bible makes claim to His perfection, and I believe it defends that premise well. You can make any argument you like against His perfection, I'm quite certain that I can produce a plausible counter argument. This is not to prove definitively that He is indeed perfect, but it does allow the possibility for Him to be perfect. If it is possible, the you must grant that it is equally possible that we are made in His image (minus the perfection) rather than the other way around (which cannot account for said perfection).
3) Miracles. Coming from a Christian background, you undoubtedly are aware of the presence of miracles within the Bible. I will focus on one because I'm not arguing for their existence so much as their validity as evidence for us being made in God's image. Basically, I'm arguing that if God is made in our image, how did people in Jesus' time account for miracle? Take, for instance, the immaculate conception. Now, whatever may have actually happened (I believe in its truth, I'm guessing you don't), Joseph believed it really happened. Now, whatever you might believe about history prior to this event, we both would agree that, at the very least, about 6000 years of procreation had been going on. This means that Joesph knew very well where babies come from. This was not a 1st century misunderstanding of a basic law of our survival (sex makes babies), he literally believed that not only was Mary pregnant, but she became so without having sex. Not only that, but people in general from that time on continued to believe it. Why? How does your view account for this? How can we, who cannot perform miracles (at least from your perspective), project this ability onto someone else? Where does such a concept originate save from experience?
4) Change. When a human being goes through a particularly moving or traumatic experience, what do they often say about it? "It changed me." Whether or not they admit it, people do change over time. Sure there are some aspects that don't, but no human every retains their exact character and preferences over a life time. How then do we come up with a God who does not change (Numbers 23:19, Psalm 102:27, Malachi 3:6)? Throughout the Bible, we see a God who remains the same. He is not affected by what we do, His character and preference are no different in Genesis than they are in Revelation. If we were truly projecting our image onto God, then He would change in some way, shape, or form of the term.
5) Origin. If you are correct and God is nothing more than what we make Him to be, then where does our "image" come from? Better stated, if God's character originates with us, where does our character come from? What gives us personality? You can say it came from evolution, but then, where does evolution come from? What started that process and made it work in such a way that gave it the ability to produce personality? There has to be a beginning somewhere. This is not just a philosophical consideration, there is scientific evidence that there had to be a beginning (see the Borde-Guth-Vilenkin theorem). I would make the argument that it started with God.
That's all I can come with at present and I may come up with more later, but I'm sure that's enough to get a good discussion going. Please also take your time in responding, I would rather a delayed but well thought out response than a quick one that is formulated poorly. This is not a matter of winning or losing for me (I'm assuming that's the case for you as well), I am well aware that I have little chance of truly convincing you. If anything this will help me confirm my own views (which it already has) and help me when I face this issue again.