Augustine of Hippo, On the Merits and Forgiveness of Sins, and on the Baptism of Infants II.56: The Case of David, in Illustration

Some such thought has occurred to us about the patriarch David, in the Book of Kings. After the prophet was sent to him, and threatened him with the evils which were to arise from the anger of God on account of the sin which he had committed, he obtained pardon by the confession of his sin, and the prophet replied that the shame and crime had been remitted to him; but yet, for all that, the evils with which God had threatened him followed in due course, so that he was brought low by his son. Now why is not an objection at once raised here: “If it was on account of his sin that God threatened him, why, when the sin was forgiven, did He fulfil His threat?” except because, if the cavil had been raised, it would have been most correctly answered, that the remission of the sin was given that the man might not be hindered from gaining the life eternal, but the threatened evil was still carried into effect, in order that the man’s piety might be exercised and approved in the lowly condition to which he was reduced. Thus also God has both inflicted on man the death of his body, because of his sin, and, after his sins are forgiven, has not released him in order that he may be exercised in righteousness.