The main theme of Christina Rossetti's 1861 narrative poem "Up-Hill" is essentially the meaning of life and death. The journey of life is one of spiritual nature; however, it is not an easy one. It can be a challenge—an uphill battle—but a challenge that one must learn how to overcome.

There are two speakers in the poem: one that asks questions about a road ahead and one that answers. The road is basically a metaphor for the soul's journey toward heaven, as well as one's life journey from their birth to their death. In this context, it becomes clear that the poem has religious undertones; thus, it can be argued that life's journey is essentially the soul's journey to salvation and deliverance from sin and evil. Everyone will walk this uphill road, and everyone will face their own individual hardships as well as joys, and at the end of the road, we will all finally get the chance to rest and ultimately find peace.

In this sense, the imminence of death is also one of the main themes. Death, or the final destination, is metaphorically presented by the "inn," which is described as a comfortable place that has "beds for everyone," where everyone can lie down and relax. However, Rossetti also writes, "Of labor you shall find the sum." This basically means that we will all face the consequences of our actions and that how "comfortable or uncomfortable" our souls will be in heaven or even hell depends on our choices in life. The comfort of our final beds is determined by our actions and behavior—the better we are as persons in life, the better and more comfortable our stay at the "inn" will be.

“Up-Hill” by Christina Rossetti can be seen as an allegory on the journey of life or, more specifically, on the spiritual journey of the soul—the Christian soul, to be more precise. Rossetti makes it clear that this journey is long and hard, with many challenges along the way.

The road winds “up-hill all the way” and will take a whole day's journey. Here, a whole day stands for an entire lifetime. There can be no doubt that Rossetti wishes to convey the impression that a life's journey, or the journey of the Christian soul, is not supposed to be easy.

To be sure, rest can be found from the rigors of the journey, but only in death. Entering eternity at the end of our lives is represented in the poem by the metaphor of the inn, where the individual soul shall find rest, along with all the other souls who've previously made the journey. There is ample room at the inn for all who make the trek, perhaps an allusion to the words of Jesus in John 14:2, which Rossetti would have known very well:

In my Father's house are many mansions.... I go to prepare a place for you. (KJV).

This is the ultimate destination for the Christian believer, one who has faithfully followed the long, winding road of life while remaining on the path of righteousness.

The main theme of this poem is that life is hard and full of challenges but that there is a place to rest for all in the end. Rossetti uses the metaphor of a road that "wind[s] up-hill" to signify life and its difficulties, and the speaker claims that the journey is long and challenging from start to finish (like climbing a large hill or mountain). However, a traveler "cannot miss that inn" which waits for all travelers at the end of the day's journey—the "day" is another metaphor for a lifetime—and no traveler is kept waiting for a place once they reach the inn. The "inn," then is a metaphor for death, where there are "beds for all who come." Everyone reaches eternal rest, and this metaphor provides a reassuring image of what awaits us after death: a comfortable place to rest, free from worry or struggle.

"Up-Hill" is a short poem comparing life to a journey.  It contains two voices.  One poses questions, the other answers.  The voice asking the question sounds worried and leary of the end of the journey, and seeks solace in hearing that the end contains a peaceful rest.

As in many of Christina Rossetti's poems, a prominent theme of "Up-Hill" is the idea of life and death, with a particular focus on the worry about what happens at the end of life.  Some have suggested Rossetti's Anabaptist background contributed to her fascination of life after death.  Others suggest that as a female poet in the 19th century, Rossetti might have adopted the idea of many female authors at that time, which was to become isolated in order to be successful (or viewed as successful) in the art of writing.  This isolation resulted in introspective and often morbid writing.