Saint Christopher was one of the most popular saints, and demand for his printed image at fairs and markets must have always been strong. This is in spite of the fact that by 1521, when Dürer made this print, the cult of saints in general, and Saint Christopher in particular, began to be rejected by the reformation.
Dürer depicts the moment when the giant Reprobus turns his head and realises who this improbably heavy child he is carrying really is, and that his weight is due to him carrying the sins of the world. For his service Reprobus was baptised in mid-stream, becoming Christopherus, the 'Bearer of Christ'. Dürer's version is a virtuoso little night scene. In fine early impressions, such as the present one, the darkness is further emphasised by a deliberate plate tone.
It is interesting to note that Saint Christopher's feast day was removed from the universal calendar of saints by the Vatican in 1969 due to lack of historical evidence. It is unclear whether the man in question actually existed and if so, whether he lived a life of holiness.