Lyric discussion by Raumoriel 

To me, this is about someone who feels very very bad about himself and who condemns himself for his (real or imagined) sinfulness.

The first two verses are all about feeling a great temptation, a physically tangible urge to sin, and taking drastic measures in order to resist. He locks himself away to avoid making a bad choice, or any choice at all. He is incredibly fearful, anxious, and physically tense, and maybe he relieves that tension in sex, as is later suggested: "I took the road and I fucked it all away".

The third verse actually makes a lot of sense when thinking of the song's story as trying to stay away from a toxic partner after the relationship is over, possibly through cheating. And I believe that he did something bad, either to her or to the person she was cheating with, because in verse four, he initially speaks in the past tense, indicating that he did something bad while knowing full well that he might and still risking it. Now he doesn't want to repeat the same mistake, so he tries hard to steer clear of sin.

He begs for someone to help him, to "Hold [his] hand /consign [him] not to darkness", but he won't accept the "grace" or forgiveness this person - be it Jesus or simply a friend - offers because he believes himself to be a sinner at heart ("crawl on my belly" -> biblical snake) precisely because resisting takes such a huge effort.

Only in the last line is he beginning to see hope, cluthing at a straw: "But in this twilight our choices seal our fate". He's finally realizing that by choosing not to sin, he has already proven himself, that it's not his animal urges that count but his decisions.

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