I believe that this song is about (or for?) the people who have a dream but struggle to get there. Let me back up my interpretation.

The first hint I got went from another song. In "Hungry for Heaven", one verse says "You're in danger, the last of a line, but the vision lasts forever". Now this song is about dreamers trying to reach their dream, literally "hungry for heaven", but who "need a little hell", meaning they must overcome hardships to get there. In this song, the line seems to refer to dreamers, and the last in line may not see his dream come true.

Let's go back to "Last in Line". The first part corresponds : a "ship without a storm", the "cold without the warm", the "laugh without a tear", the "hope without the fear" all refer to a concept that is not complete without its nemesis. This sentence says it all : "Light inside the darkness that it needs". The dream needs hardships to come true. This part ends with the expression of renouncement : "we are coming home"

In the second part, a few second later, this is opposed with a "we may never (x3) come home". We're off to the dream, to the "witch". Now, the rest of the song shows that dreams are ambiguous, both bad and good. Only when we accomplish them can we say we were "evil or divine". I personally think it refers to whether you decided that the end justifies the means, or not. And Dio tells us the answer is not black or white, but grey : "it's the angel or the beast, and the answer lies between"

Buuut the most important part is not the goal, it is the hardships. The only way to emerge victorious, to "release yourself" is "down", through hell. Again this notion is present in "Hungry for Heaven", but also "Pain" "The Sacred Heart" and so on.
But not to worry, because we'll find help. We're "fire" (emotions) and "stone" (tenacity). We're also not alone, as "we" is omnipresent. Finally, the hardships themselves are worth the try : "the magic that we'll feel is worth a lifetime"; "the thrill of just the chase is worth the pain". Really an empowering song, one of my favorites... maybe because I am not the first in my own line, ahahah!