I'm not assuming anything I am simply pointing out the immutable law of cause and effect which clearly has been pointed out by others elsewhere that this governs our very existence, I am only basing my opinion on observation of the universe and that of others and of the natural world we live in. If someone or a group of people are going to attempt to prove the existence of natural phenomena through natural processes the problem is proving it true by natural processes or through nature alone, but no scientists or groups of scientists anywhere on earth has been able to prove it irrefutably. People choose to believe what ever they choose to and many have an opinion how the universe came into existence or how life started on planet earth, was it Prof Stephen Hawkings who suggested the multi universe hypothesis? others have suggested gradual evolution like Charles Darwin, nothing inherently wrong with that but there is no irrefutable proof of any of it, just postulation and opinions, that's all. Life begets life and there is no escaping that fact, how all of it came about in the very first place is disputed heavily. We agree to disagree. I'm sure if and when irrefutable proof is certainly found that it will be all over the news. Take care have a nice day.
There is a great deal of difference between a rational explanation that matches every single piece of evidence and an "explanation" that simply states "it's magic". They're simply not the same thing at all.
There is also a great deal of difference between "we don't know" and "it's magic". They're also not the same thing at all.
And yes, you are assuming that the universe was created by a god. You stated so explicitly when you described it as "a miraculous event or thaumaturgic." You're making the "it's magic" statement, since a miracle is also magic. You have also stated it again just now when you stated that the universe was created by an external cause.
There is plenty of evidence of things happening in the universe that have no apparent cause. "the immutable law of cause and effect" might not be so immutable at a very small scale. Or maybe it's simply that no human understands the cause yet.
You're apparently failing to understand a key point of science, namely that it's willing to make rational explanations based on evidence. For that reason, strictly speaking no scientific theory should ever be considered irrefutably proven. If an explanation is considered irrefutably proven, it is a declaration that if any evidence that the explanation is wrong to any extent in any way in any circumstances is ever discovered then the evidence must be ignored. That's the opposite of science. It's also a declaration that if any other rational explanation that matches all known evidence is ever deduced it must be decreed to be false without consideration of its merits. That's the opposite of science. You are ordering science to be anti-science. Do you understand how wrong that is?
Of course, some theories can be treated as proven on a day to day basis. When an explanation holds up every time to every evidence from every experiment and every observation, over and over again from a multitude of independent observers, and that explanation correctly predicts what will happen in specific circumstances, all the time, every time, it can reasonably be treated as proven on a day to day basis. But even then, scientists will allow for the possibility of change, accept the possibility that an explanation was in some way incomplete or even incorrect. Even really fundamental theories that underpin many other things and which have overwhelming evidence for them, far more evidence than would be required to consider something proven outside of a scientific context. An example that comes to mind was the suggestion of the existence of superluminal neutrinos a few years back. That was an extremely radical idea because it quite fundamentally contradicts the most basic part of the theory of relativity. Rather a big deal, since much of modern knowledge is built partly on relativity. Did scientists treat the suggestion as heresy? No. They treated it as probably a mistake but also an opportunity. There were theoretical physicists who were downright happy about it because if superluminal neutrinos did exist then that meant there was suddenly an unexpected new area of knowledge to seek and that's a great treasure to scientist.
You're treating science as a religion. You're fundamentally wrong to do so.