To answer this question, one would have to have some prior notion of what theism is and what science is, and these are not univocal concepts. The question without more really makes no sense. Our theistic traditions have their ultimate historical origins in very literal and obviously false beliefs, and over time, for many people, these belief systems refine themselves, purging themselves of the obviously false. But in the process of doing so, the remaining beliefs become less and less susceptible to assessment empirically, and, alas, their meaning becomes less and less clear. For people like Dawkins, life is made most comfortable if his model of what religious belief is is kept as close as possible to the literal, concrete and obviously false, because it makes his toolkit for dealing with it most relevant. At the other end of the spectrum, if someone says “when I say there is a God, I mean that life means something, there is a power of love in the world and I am confident that love triumphs in the end,” well, how could that be wrong? (How could denying it be wrong either?) But I’m not comfortable calling such views philosophical, which implies that there are rational arguments possible for and against, and this kind of thing is just too indeterminate to admit of any rational argument. When intelligent people attack Dawkins, they attack him in part because he “doesn’t get” these less concrete forms of religious experience. But is that entirely fair? After all, it’s not clear that the increasing vagueness makes these kinds of experiences, beliefs and attitudes better, it just means that they are more difficult to pin down and thus more difficult to attack. That’s not necessarily an intellectual virtue. What’s more, it’s not clear that anyone would be in the least bit interested in a belief that began so vaguely. Rather, the interest in such beliefs comes from the residual associations they have with the more concrete and obviously false superstitions they evolved from. As for real philosophy, well, Anselm purports to prove that a perfect being exists. Sartre used a version of this very argument to prove that the world exists. The interest of Anselm’s argument depends on what it doesn’t say, which is “identify this being with the fascinating character portrayed in Genesis.” But not only is there is no argument for such identifications, such identifications depend precisely on hanging onto those aspects of religious belief we have the least reason to hang onto.
One last point: what makes skeptical responses to religion powerful is not the refusal to believe weird things without evidence, nor even the availability of scientific explanations that rival religious explanations (e.g., in biology), but the availability of nonreligious explanations for religious phenomena themselves. Yes, Darwin has harmed religious belief, but perhaps scholars like Wellhausen who discovered that Genesis (and the rest of the Torah) appears to have been cobbled together from sources with different assumptions, backgrounds and motives harmed it far far more.