It is not at all difficult to declare that the entire Universe could not be created ex nihilo, out of nothing. It is easy to prove that the Gospels contradict one another. It is easy to disprove much of the nonsense that is in the Bible. It is easy to prove that there was no eclipse at the time of the crucifixion.
It is easier to accept that the matter, energy and dark matter that comprise the Universe have always existed than to prove that nothing existed at one time but an omnipotent, omniscient, omnipresent, invisible, intangible, odorless entity alone was all that existed.
The Biblical story is easy to disprove. If you could disprove a scientific explanation, it would not prove the Biblical myth to be true.
The origin of life begins when a complex protein manages to duplicate itself. Tihs could have happened on Earth, it could have happen elsewhere and have managed to come to Earth. In a billion years, many possibilities exist, but some are far more likely than others.
The Big Bang was not the beginning of everything: it is merely as far back in time as we can speculate about. It does not mean that prior to the Big Bang, nothing existed.