The problem is that they are not willing to admit that the evidence of God's Word is the entire Universe.
The universe, insofar as it is ever-expanding presence of physical matter and energy we can explore, is seemingly explained away as coming into existence "just because" and without any legitimate physical explanation. Theories abound, but no one can really explain from where the universe came. Singularity has been a popular theory but it is fraught with physical contradiction. Heisenberg's Uncertainty Principle pretty much negates the possibility of ever having all the atoms of the universe in one place and accounted for.
In addition, we have to consider that everything we know of materially, every element, compound, molecule, subatomic particle and atom, only makes up 4% of the universe. The rest is dark matter and dark energy, of which we know virtually nothing about. But there is something much more mysterious than dark energy or the physical universe itself, and that is TIME.
I belive that TIME is the ultimate "proof" for God's existence. Without Time, nothing in the universe matters and nothing can exist. To "exist" something must have time and space to exist in. We can measure the passing of time but the existence of time itself is elusive.