Why do atheists keep using their stuipid guess theorys to explain the universe

Because God put the evidence in support of the theories in the universe
Why did God do that?
And the theory of evolution is supported by much more evidence than the theory of creation.
Even the supporting evidence for the theory of creation is flawed as the Bible doesn't even agree with itself on how many animals were taken on the Ark.
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And your mathematician's accumulated estimates are all based on human judgement - unless you claim that he is inerrant

Evolution has nothing to do with atheism.
Evolution has nothing to say about the origin of the universe.
Evolution is not random.
Evolution does not say that life emerged from the big bang.
The big bang was not an explosion.

You have no idea what evolution is and what it isn't.

You miss the point entirely. The explanations you call 'stupid' are not the beliefs of atheists, they are the best explanations of science. And, Scientific explanation is neither theistic nor atheistic - it is just simply process driven, evidence-based theory without reliance on divine magic.

The same science that brought us medicine that saves lives, the technology that improves lives, even the very infrastructure and tools that allow this Forum to exist, also tell us quite clearly that species evolved into the diversity we see over millions of years, and provides some understanding of how this evolution occurred - but not yet fully.

Science is a gift from God. It is ironic that to be wise stewards of this gift, we have to be very careful to leave the hand of God out of the calculus of scientific theory. Doing so does not deny God. But when anyone asserts that it does (either atheist or believer) then they are not doing science or defending religion against science - they are just spewing their ignorance and intolerance.