I'm not suggesting a "God of the Gaps" where scientific blanks infer the existence of God. It's an illustration to say that belief in a God isn't unreasonable.
Well, as always, you have to qualify these things.
The Deistic god of which you speak--God as a first uncaused cause--might be a possibility. But as it is only one an infinite number of equally plausible possibilities, I don't find it reasonable to actively believe in it.
(Further, most people do not believe in that god. Billions of people believe in a personal god that gives a fuck about us; one that answers prayers and keeps tabs on our Earthly affairs; one that is omnipotent and omniscient and morally perfect. That god is flatly incompatible with the relative anarchy of the world.)