World Whisperer by Rachel Devenish Ford

A devastating sacrifice. A daring rescue. A new world of magic unveiled.

As a fourteen-year-old outsider girl in the Worker village, Isika is destined for endless drudgery, serving her priest stepfather and worshiping the four goddesses of the Worker people. She doesn’t fit in and she hates the goddesses, but her mother is dead, and her three remaining siblings need her to be good and keep them safe. She can’t think of anything beyond surviving each day and trying to avoid her stepfather’s wrath.

Until he decides to sacrifice her youngest brother to the goddesses.
And Isika decides that enough is enough.

She sets out on a journey to save her brother, facing an unknown world outside the walls of the Worker village. In the new world, ancient gifts awaken within her as she finds more beauty and more trouble than she could have imagined.