While the Gospels make a number of references to eternal damnation, they do not appear to directly mention purgatory, which is a strong precept of the Catholic faith. My question therefore is: according to the Catholic Church, are there verses in the Gospels which indirectly refer to the existence or otherwise of purgatory?
In the encyclical Spe Salvi, Pope Benedict XVI provides an interpretation of the parable of the rich man and Lazarus in which the rich man is in Purgatory:
In the parable of the rich man and Lazarus (cf. Lk 16:19-31), Jesus admonishes us through the image of a soul destroyed by arrogance and opulence, who has created an impassable chasm between himself and the poor man; the chasm of being trapped within material pleasures; the chasm of forgetting the other, of incapacity to love, which then becomes a burning and unquenchable thirst. We must note that in this parable Jesus is not referring to the final destiny after the Last Judgement, but is taking up a notion found, inter alia, in early Judaism, namely that of an intermediate state between death and resurrection, a state in which the final sentence is yet to be pronounced.
This early Jewish idea of an intermediate state includes the view that these souls are not simply in a sort of temporary custody but, as the parable of the rich man illustrates, are already being punished or are experiencing a provisional form of bliss. There is also the idea that this state can involve purification and healing which mature the soul for communion with God. The early Church took up these concepts, and in the Western Church they gradually developed into the doctrine of Purgatory.