This book is on pre-order until book delivery arrives. 
 
Hail the Rising Ride by Kat Kraehen:
 
Prim and prideful Ione possesses the Moon Goddess’s spirit and a harrowing fate: overpower the wrathful Sun God and sweep His murderous pyromancers into the sea. But attaining divine ascension is easier said than done, and the longer Ione takes to save her people, the more impatient her conniving archpriest becomes.

Quiet, distrusting Lina has had more than enough of bloodshed. After escaping immolation by Sun-worshipers, she gains a new lease on life as a nameless acolyte of the Moon Goddess. That is until she catches the eye of Lady Ione, whose captivation with Lina has caused the Goddess to stir within her for the first time.

As temples burn and Ione’s archpriest launches treacherous gambits of his own, Ione and Lina’s alliance deepens into something neither of them anticipated. If Ione’s enemies reach her before she can awaken the Moon Goddess, everyone she loves will go up in flames.

But if she succeeds, the Sun cult will be annihilated - including Lina, whose past as a Sun priestess cannot remain hidden forever.