"Grace is the incomprehensible fact that God is well pleased with a man, and that a man can rejoice in God....grace means bearing witness to the faithfulness of God which a man has encountered in Christ, and which, when it is encountered and recognized, requires a corresponding fidelity towards God" (31).
"He who is under grace can no more adjust himself comfortably to sin than the sinner can toy with grace as with an alternative human possibility" (217).
"To the man under grace, righteousness is not a possibility, but a necessity; not a disposition subject to change, but the inexorable meaning of life; not a condition possessing varying degrees of healthiness, but the condition by which existence is itself determined; not that which he possesses, but that which possesses him" (220).
"If we are able to endure life apart from this possibility [of obedience]; if we are content with something less; if we trim and adjust grace so that it dovetails in with other possibilities;--grace is not grace. If we are able to escape from that naturally Christian--Medieval!--disturbance of soul; if all that is in us does not stretch out towards a sanctified life prepared for and open to the righteousness of God; if we do not long for a life running so nigh to the righteousness of God that it would break visibly through in our members, in our mortal body;--grace is not grace" (223).
Quotations from Karl Barth, The Epistle to the Romans(Oxford: 1968).