Why do many religious people (of different faiths) think that science is supposed to be deductive...?

I couldn't agree more, and I've never disputed that scientific investigation is inductive. But when people start claiming Darwinian evolution is a fact, they are then implying that Darwinian theory is exclusively deductive, but an objective examination of the hypothesis clearly indicates that it is not. Additionally, many naturalists, atheists, and agnostics speak of science as if it is omniscient, infallible, and entirely deductive, but honest and intelligent people--the ones who really care about upholding the integrity of scientific inquiry, freely admit science isn't the only theory of knowledge that determines all truth and admit its limitations. So what I think you're seeing is only a sort of backlash against all these pronouncements of scientism, mixed in with misunderstandings of the inherent nature of science itself.