Hi, scraf. This post isn't so much directed at you but more of a general statement for the entire thread. I am mostly replying to your post since that is what inspired me to write.
There is a problem with this conversation, and that is the fact that "know" can have several different meanings.
In epistemology, knowledge is "justified true belief" (ignoring the objections of the epistemic minimalists -- sorry holmes). That is, if one believes that the sun will come up tomorrow (and nothing here requires the belief to be 100% certain -- just reasonably certain), one has a reasonable justification to believe that the sun will come up tomorrow, and the sun does in fact come up tomorrow (making it a true belief), then the person did, in fact, "know" that the sun was going to come up the next day.
Of course, this is not the meaning that people are using. This sort of argument is very much a heavily philosophical one, and in my opinion if one is going to get this deep into philosophy then one should be careful to use words with a technically precise meaning.
That being as it were, most people are using the word "know", it appears, to mean "believe with 100% certainty, with no doubts whatsoever." Far be it for me to try to stop the incoming tide, so I will accept that as the working definition.
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In that case, it is perfectly possible for someone to acknowledge, intellectually, that there is a very, very small chance that the sun will not come up tomorrow, yet nonetheless have no doubts whatsoever that the sun will come up tomorrow. For many people, perhaps most, belief is not an intellectual state but an emotional one. It is not hard for some to take a very, very small probabibility and turn it into, as far as doubts are concerned, into no doubt whatsoever -- human psychology is what it is.
I am one of these people, it seems. I can acknowledge, intellectually, that the sun just might not come up tomorrow -- I am knowledgeable enough in science to know of possible not completely unreasonable science fiction scenarios where the sun may be prevented from shining. However, there is no doubt whatsoever in my mind that the sun will in fact come up tomorrow. Such is my psychology.
Now let us consider the case in the OP, namely whether the "God of the Bible" actually exits. I can imagine that a Very Powerful Being interacted with the societies of the Middle East during the Bronze Age, leading to the development of the Hebrew culture which then produced the rabbi Jesus of Nazareth. I can even acknowledge, intellectually, that this interaction occurred up to and including interaction with Jesus and the early Christian saints. In fact, even in regards to my beliefs (as opposed a purely intellectual acknowledgement of the actual possibility), I admit I am probably not 100% certain that a Very Powerful Being did not interact with various individuals in the Middle East from the Bronze Age until the early Christian era, with the Bible being a very inaccurate description of these interactions.
However, if you try to give the hypothesis that a Very Powerful Being attempted to guide people to live a Good and Decent Life by not only interacting with individuals but also by indirectly inspiring writers to write the correct things, then my belief goes to zero. I can
intellectually acknowledge the possibility that a Very Powerful Being was intent enough to guide the Middle East societies and later Roman Empire by indirectly inspiring various literary works, but now the possibility becomes so small that my mind turns it into 0 possibility as far as actual belief. I have no doubt whatsoever that such a thing did not occur.
We have a further problem with the OP. The OP talks about the possibility of the existence of "the God of the Bible". The involves, I assume, such things as the creation of the universe, an interest in human beings and how they live, the promotion of some sort of moral code that includes worship of said being, the continued existence of a person after death and the ability of the god to affect the state of the person in the afterlife, the doling out of punishments and rewards based on whether one accepted the death of the incarnation of this god as a human sacrifice, and so forth and so on. Well, the sum of all of this is so fraught with contradictions and implausibilities that even purely intellectually, without regard to belief, I don't see how someone can accept this.
So, I am 100% certain that the Abrahamic god does not exist. One may claim that it is irrational, but so be it. I can acknowledge that there is a very small possibility that a Very Powerful Being has attempted to guide Western Civilization by inspiring various literary works as well as interacting with various prophets and that the Bible is a very inaccurate description of this Being and its interactions; nonetheless I have no doubts that such a thing did not occur.
The basic tenets of Christianity, at least as understood by traditional Christians, is, in my opinion, not even a starter. The most basic tenets of the tradition, conservative, evangelical Christians are so contradictory that even an intellectual acceptance of the basic tenets become unreasonable to the point that, for me at least, it is impossible.
Kings were put to death long before 21 January 1793. But regicides of earlier times and their followers were interested in attacking the person, not the principle, of the king. They wanted another king, and that was all. It never occurred to them that the throne could remain empty forever. -- Albert Camus