1 sn The name Sarai (a variant spelling of “Sarah”) means “princess” (or “lady”). Sharratu was the name of the wife of the moon god Sin. The original name may reflect the culture out of which the patriarch was called, for the family did worship other gods in Mesopotamia.
2 sn The name Milcah means “Queen.” But more to the point here is the fact that Malkatu was a title for Ishtar, the daughter of the moon god. If the women were named after such titles (and there is no evidence that this was the motivation for naming the girls “Princess” or “Queen”), that would not necessarily imply anything about the faith of the two women themselves.