"Eyes within the dark were watching". Satan is always watching you. Waiting for opportunity to get you in his trap.
"Without your love in my life, Alone I walk in the night". Without true love or Gods love you walk alone against the devil.
"She was up a stair to nowhere, A room forever I'll remember, She stared as though I should have known her, Tell me what's your pain or pleasure". Tempted by a prostitute, he remembers the room in which he had sex with her, Falling into satans trap.
"She said reality is a knife, When there's no love in your life, And merciful is the night". Again, without true love or Gods love life becomes hell, and death is merciful. Better than a life of torture.