Barth: divine immutability as divine constancy

“God is in Himself the living God, that His eternal being of and by Himself has not to be understood as a being which is inactive because of its pure deity, but as a being which is supremely active in a positing of itself which is eternally new. His immutability is not a holy immobility and rigidity, a divine death, but the constancy of His faithfulness to Himself continually reaffirming itself in freedom. His unity and uniqueness are not the poverty of an exalted divine isolation, but the richness of the one eternal origin and basis and essence of all fellowship. The fact that according to His revelation God is the triune God means that He is in Himself the living God.”

—Karl Barth, Church Dogmatics IV.1, trans. G. W. Bromiley (Edinburgh: T&T Clark, 1956), 561.