"The only thing we can and should trust is the sciences" (John Loftus, The Christian Delusion, 89)
Unfortunately, this claim isn't a deliverance of any natural science. Science can't tell us something like this.
Furthermore, since the claim includes a normative prescription (i.e., "should"), science is impotent to tell us this.
Therefore, we shouldn't trust this claim.
Besides this, there are many things science cannot give us the answers to. I already mentioned normative truths (either ethical or rational), but there's also the reliability of my senses, the laws of logic, the existence of an external world, the existence of other minds, and a justification of the scientific enterprise itself. None of these things are given to us by science; indeed, most of them are presupposed by science.
I really can't fathom why some of the names that blurbed this book on the back cover did so. Michael Martin called it "arguably the best critique of the Christian faith the world has ever known." But of course, among its many other problems, Loftus' claim I quoted above rules out many of the chapters in the book as not worthy of our trust. Indeed, I've just been cherry picking stuff, a real critique would reveal hundreds of other errors of a similar nature, or worse.