As with so many of his poems, Eliot introduces "The Love Song of J. Alfred Prufrock" with an epigraph. It's an extended quotation from Dante's Inferno, a work that Eliot especially venerated. In it, the damned Guido de Montefeltro confesses his sins to Dante, believing him to be already dead and in Hell. Prufrock, too, proceeds to confess his sins; although, they are much less serious than those of the fraudulent monk.
Prufrock sins by the very act of participating in a life of crushing middle-class boredom, an enervated existence which is marked by an absence of any spiritual depth. Prufrock is all too aware of his deficiencies in this regard, yet cannot summon up the strength to escape the shabby, sinful world he inhabits to follow a more satisfying, spiritual path in life. He desperately wants to rise above his stultifying, bourgeois existence:
I am Lazarus, come from the dead, / Come back to tell you all, I shall tell you all.
But he can't, and he won't. He's too much of a coward, too weak a personality, too spiritually enervated to do what he must. And so he's condemned to remain a sinner in a sinful world, no nearer to hope or salvation.