The he loses.
The entire basis of evolution is that everything evolved over time from a single cell that somehow contained the genetic information for everything that ever lived; plant or animal. This cell may have come about through the impossible process of abiogenesis or it could have come from outer space; though we deny that there IS other life in outer space. Regardless, the claim is that this cell which is introduced into what is probably a liquid environment somehow finds things to eat; that it somehow finds a way to reproduce; and that it somehow finds a way to escape the contained environment before it exhausts its food supply. With no natural predators and nothing to force adaptation, it somehow adapts anyway acquiring through some unknown magic process we call benevolent mutations all the genetic information required to go from being unicellular to becoming a sentient being able to concoct such a wild fabrication and call it science.
Add to this the requirement that he must prove conclusively that this mechanism is not only the best explanation for the origins of life, it is the ONLY mechanism to explain the origin of life. He must show that all the incredible organization and detail in the universe could somehow come about on its own without a designer. Beyond that, he must explain how millions of people could have supernatural encounters with a supernatural force that supposedly doesn't exist. If one is to argue using only natural laws, then one must first ascertain that natural law and ONLY natural law is the mechanism by which creation came about.
There is not one single theory of origination that can explain the origin of everything from nothingness. If God can create the universe, then He can do it as He said He did; in its mature form; ready to support life. To God, the universe could be created as easily as an artist creates a scene; painting in everything exactly as it must be. Then, being God, He brings His canvas to life; an entire global ecosystem functional immediately and created in its mature state. Science cannot refute this. Science does not and cannot validate or invalidate the existence of the supernatural. However, science can be used pretty effectively to prove the evolution is nothing more than fodder for the desperate minds of atheists who want so badly not to believe in God.