How does God’s unchanging nature impact the salvation of his people? While divine immutability enjoyed a broad affirmation through much of Christian theological antiquity, it has fallen on harder times in modernity. Seen as a holdover from overly philosophical theology, divine immutability has often been characterized as rendering God static and incapable of having meaningful relationships with his creation.   This book aims to swim upstream from this claim and demonstrate that divine immutability does not handicap soteriology but is a necessary and vital component of God’s economy of redemption as triune changelessness protects and promotes the redemption of God’s creatures. By anchoring the economy of redemption in divine immutability, we see the benefit of rooting all of God’s economic work in the immanent life of God. This book aims to be a work of dogmatic theology and therefore will arrive at this thesis by way of exegetical, historical, and philosophical theology. In harmony, these fields will interact with varying deviations and denials of divine immutability and ultimately conclude that a classical articulation of God’s changelessness does most justice to the economy of redemption.