It doesn't; Sharia is the body of Islamic religious law drawn from the Quran and the teachings of the Prophet Muhammad.

While "Sharia law" is a set of religious laws, arguably made by fundamentalists, that doesn't make all religious laws made by fundamentalists "Sharia law." You're free to say it's "just like" or "analogous to," but the contention here is that it would be in everyone's best interest if we respected the meanings of words - including "literally." A Ford Focus is not literally a Toyota Corolla, though they are both sedans. In many ways, though, a Ford Focus is like a Toyota Corolla.

tl;dr "Sharia law" refers to the body of Islamic religious law drawn from the Quran and the teachings of the Prophet Muhammad, not any religious laws made by religious fundamentalists. Respecting words is a matter of respect for the subjects and fosters respect for the speaker.