Does the road wind up-hill all the way? (1)
A Christian's journey through life is often depicted as a road or path, particularly a difficult one. Lots of famous piece of literature make use of this metaphor, but a particularly influential one—John Bunyan's The Pilgrim's Progress—was a favorite of Rossetti's.
From morn to night, my friend. (4)
Introducing the dichotomy of morning and night brings a whole dark vs. light vibe into the poem, which is always useful for drawing out any good vs. evil tension that might be hiding under the surface.
Then must I knock, or call when just in sight? They will not leave you standing at that door. (11-12)
When you're dealing with poems that have a clear religious tone, it's often really helpful to make use of a concordance, a super-useful book that tells you where and how many times a word is used in the Bible. "Knock," for instance, might seem innocuous (ha ha), but if you run it through an online concordance, it shows up in a Bible verse that is especially fitting: "For everyone who asks receives, and the one who seeks finds, and to the one who knocks, the door will be opened" (Matthew 7:8).