How should Christians mourn their sin?
For many of us, especially we Protestants, it's tempting to say we shouldn't. After all, we've received the imputed righteousness of Christ--our sins are covered.
On the other hand, we cannot ignore Jesus' words: "Blessed are those who mourn." Surely, if anything is worth mourning, it is our hard-heartedness and division from our Father in Heaven. What's more, the Bible includes the book of Lamentations, suggesting that such laments are appropriate in response to our own sin.
But this mourning is not itself free from temptation. In his Institutes, John Cassian identifies two types of "dejection." He writes:
"But that dejection and sorrow which "works repentance steadfast unto salvation" is obedient, civil, humble, kindly, gentle, and patient, as it springs from the love of God, and unweariedly extends itself from desire of perfection to every bodily grief and sorrow of spirit; and somehow or other rejoicing and feeding on hope of its own profit preserves all the gentleness of courtesy and forbearance, as it has in itself all the fruits of the Holy Spirit of which the same Apostle gives the list. "But the fruit of the Spirit is love, joy, peace, forbearance, goodness, benignity, faith, mildness, modesty." But the other kind is rough, impatient, hard, full of rancour and useless grief and penal despair, and breaks down the man on whom it has fastened, and hinders him from energy and wholesome sorrow, as it is unreasonable, and not only hampers the efficacy of his prayers, but actually destroys all those fruits of the Spirit of which we spoke, which that other sorrow knows how to produce."
When confronted by sin, we are forced to choose which perspective we will examine it from. Will we see it on its own, outside the power and mercy of God? Or will we see it in the context of the eschatological judgment and final redemption that God shows the firstfruits of in Christ on the cross?
Christian dejection, to use Cassian's phrase, must take the latter perspective. Curiously, if Cassian is right, such dejection is not incompatible with joy. Rather, we must have both joy and sorrow and that at the same time.
It's not clear what the difference between Christian dejection and the other sort is, but Cassian is clear: there is a difference, and if we fall into the wrong kind, we fall into sin. We must be a sorrowful people, for we are a sinful people in a sinful world. But our sorrow must be of the right sort, lest we use it to further harden us to our good and loving God.