In the Philosophy of Religion the term ‘impassible’ describes the property of God’s existence whereby God’s character is unchangeable.

God does not suffer changes in mood or disposition.

The impassibility of God is rooted in both God’s omniscience and immutability. If God has knowledge of all events (past, present, and future) there is nothing that will, or can, happen that will be unknown to God. Thus, God is never surprised, shocked, or taken aback which are the causes of change in mood.

Also since none of God’s essential qualities can change (i.e., God is immutable) God cannot loose or gain anything that would cause a change in disposition.