Well, let me see if I can sort this out for you. You see, atheists DON'T think that they know it all... in fact they KNOW that they don't know it all. That is because they are able to tell the difference between things that they know, and things that they DON'T know. So... when they DON'T know something, they say "We don't know." That is called 'intellectual honesty'... and it primarily means the willingness to question and doubt one's own assumptions.
We ALSO know that all scientific 'knowledge' is 'provisional'... and that means that is subject to be modified, improved, etc., as additional facts becomes available. Take the 'Theory of Evolution', for example... it provides an explanatory framework for the OBSERVED FACT that the genetic makeup of populations of organisms (creatures) changes, over time. We even know how it happens. But we are now in the process of digging up fossils, in order to paint a more complete picture of the evolutionary steps that actually occurred in the past. Think of a fossil as a low-resolution snapshot of the gene pool of a particular population of organisms at a certain space-time coordinate... we are trying to see where each one fits in the big jigsaw puzzle. There are still a lot of blanks, where we haven't found the pieces yet... but we're workig on it... and we haven't been at it all that long. Give it another 300 or 500 years or so. This has absolutely NOTHING to do with 'proving' evolution... it does not need to be 'proved'... and science doesn't 'prove' things, anyway... it EXPLAINS facts. These efforts have ONLY to do with building our knowledge-base... i.e., finding MORE facts, in order to perfect our understanding of what ACTUALLY went on.
Religious types, on the other hand, are NOT capable of telling the difference between 'knowledge' and the ILLUSION of knowledge... i.e., 'belief'... a.k.a. 'self-delusion'. For the scientist, ignorance is a GOOD thing... it defines their work-scope... tells them what they need to be working on... provides job-security. For the religious type, though, ignorance is something to be covered up and denied, under a warm fuzzy blanket, embroidered with the message "God did it."
Your question reveals that the foolishness which serves you as a substitute for knowledge and reason is a logical fallacy (a flaw in thinking) known as the "Argument From Incredulity"... which is a sub-category of the "Argumentum ad Ignorantiam" (Argument From Ignorance). It is also known as the 'Divine Fallacy'. It goes something like this: "I can't conceive of (or imagine) how this might have come to be; therefore, God did it."
That does not point to a limitation of science, or of nature... rather, it illuminates a limitation of YOUR knowledge and/or intellect. Also, it is intellectually dishonest, since it does not (as scientists do) ACKNOWLEDGE the limitation of knowledge... it merely invokes the fanciful idea of a supernatural creator-entity to manifest the ILLUSION that your ideas correlate to 'facts'. Finally... it reveals that you presume, for yourself, a form of omniscience... thinking that goes like this: "If this were understandable, then I should be able to understand (or imagine) it. Since I do NOT (can not) understand (or imagine) it... it logically follows that it is NOT understandable... by ANYONE. Since it is NOT understandable by anyone, it logically follows that it cannot be 'true'. Therefore... God did it." (See? Right back to the Argument from Incredulity.)
'Faith' (wishful, magical thinking) is a lame and pathetic substitute for 'evidence'.
'Belief' (the internalized 'certainty' that you are privy to the 'truth' pertaining to some fundamental aspect of existence and/or reality) is a lame and pathetic substitute for 'knowledge'... i.e., it is the ILLUSION of knowledge.
faith + belief --> self-deception, self-delusion and willful ignorance
"The greatest obstacle to discovery is not ignorance... it is the illusion of knowledge." ~ Daniel Boorstin
"When one person suffers from a delusion, it is called insanity. When many people suffer from a delusion it is called Religion." ~ Robert M. Pirsig
THINK about this... seriously... THINK... you believe that a cosmic Jewish zombie, who is his own father, can make you live forever if you symbolically eat his flesh and telepathically tell him that you accept him as your master so he can remove an evil force from your soul that is present in humanity because a rib-woman was convinced, by a talking snake with legs, to eat from a magical tree... (etc.)... and that there is something horribly wrong with people who ARE NOT so gullible and droolingly stupid as to believe such outrageously ridiculous codswallop.
Now... here's a NEWS FLASH: sane people do not believe such nonsense.
I hope that helped clear things up for you.
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