No, immateriality alone is not the reason we cannot prove that God exists. The reason is because God does not want us to be able to prove He exists, and since God is Omnipotent, God calls the shots.
God could interact with this world without affecting the laws of physics. For example, God could communicate to our minds and cause us to take a course of action. Of course there is no way to prove that. Nothing God does can ever be proven, but that does not mean God does not do anything; we just cannot state it as a fact, and that is why it is a belief.
I find it rather silly when Christians go on about what God is "doing" in their lives, as if they could ever know that God was involved in whatever happened... I coined the phrase "naive believer syndrome" several years ago on a Baha'i forum and they got up in arms. Believers like to think they know what God is doing but that is so naive. We can believe that God did something in our life but we can never know it.
I do not believe God exists because a Messenger of God exists; rather I believe that the Messenger of God is the evidence that God exists. God simply exists and would exist even if there were no Messengers. Of course there would be no way to know that God exists if God never sent Messengers, which is one reason God sends them.
I agree. You should never believe that something exists just because other people believe it exists. That is the worst possible reason to believe in God. Baha'u'llah said that.
In principle, it means that it has to come from within you, something you discovered yourself, not someone else's truth. If it does not ring true for you you should not accept it as true.
I am not God, so I do not know why it is so much more difficult for some people than for others to believe in God, and there might be reasons why it is not God's intention that everyone believes in Him.
Baha'u'llah wrote that those who make efforts will surely be guided. Motivation is very important in anything we do, it is what drives us, so if someone is not motivated they are not going to make that effort. For many decades I had no motivation so I was not guided. I still believed God existed but it meant nothing to me.
If being immaterial was not the only reason we can't prove God(s) exists, then you should not have claimed that it is. What are the other reasons we can't prove that God(s), exists? Also, unless you are a God yourself, you have no idea what is in the mind of a God. You have no idea what He thinks, wants, is, or needs. And, you certainly can't know WHY He does anything. You should really apply your "naïve believer syndrome" to yourself as well.
I do not believe God exists because a Messenger of God exists; rather I believe that the Messenger of God is the evidence that God exists. God simply exists and would exist even if there were no Messengers. Of course there would be no way to know that God exists if God never sent Messengers, which is one reason God sends them.
If you are using a Messenger of God to evidence the existence of God, then you are being implicit that a Messenger of God does actually exist. There is no difference between your two statements, since there is no evidence to support the existence of either. I believe that the Universe that exists today, is clear evidence that a God(s) does not, and cannot exist. The existence of Messengers of God(s), angels, devils, demigods, the spiritual and paranormal, miracles, souls, or a heaven, are all violations of our physical laws of reality. This would create a new causality paradigm, which would render our fundamental forces functionless and redundant. Therefore, these religious/spiritual claims need to be seriously addressed and demonstrated. Not with more empty rhetoric, self-serving excuses, fallacy-riddled logic, subjective anecdotes, and with absolutely zero evidence.
Since you seem totally perplexed why some people find it so difficult to believe in the existence of God, let me help you. EVIDENCE. It is evidence that is the source of true enlightenment. It is evidence that is the difference between what is perceived as true, and what is conceived as true. It is evidence that is the difference between what is perceived as real, and what is conceived as real. It is evidence that is the difference between what becomes practical knowledge, and what becomes abstract knowledge.
Any human being can easily be assisted in convincing himself to believe in anything. Given enough time, motivation, rewards, and positive feedback, anyone can be convinced that an afterlife, God(s), devils and angels exist. Or, can be convinced that miracles and other superstitions are real, without any need to deposit one example, one relevant demonstration, one relevant comparison, one objective/verifiable piece of evidence, or without one fallacy-free consistent argument. Unfortunately, the mind's ability to compartmentalize sensory input, has proven to be a blessing as well as a curse.
If you believe that your beliefs are perceptual in origin, then you are just deceiving yourself. Unless, belief itself is now an innate/congenital part of the human condition. I along with many Atheist have no objection to adults, believing in adult fairy tales. It is only when those fairy tales encroach into my ontologically-based reality, that my attention becomes warranted. The encroachment of Deuteronic Ethos, elitism, and intolerance, is clearly visible within society. Religious tenets exist in our public education system, our government and legal systems, our sense of morality, women's reproductive rights, our scientific principles and research practices, and in the stifling of critical/independent thinking and individualism.
If you have some innate need to depend on an imaginary interdimensional multi-omni sky daddy, to give you a sense of security, community, and inner strength, then why not just keep it to yourself? If not, lets see the evidence. Surely, the 80+% of the world's population can produce one verifiable objective evidence, to suggest the existence of anything that is supernatural or spiritual. Maybe a prayer that works? Maybe any example of the paranormal? Even a violation of the physical laws will do. So far nothing but excuses, or the old standard, "you won't understand, until you have convinced yourself that you do understand. Then you will understand".