Just wondering -- not patronising. Does everybody share the same definition of "redeemable?"
Because where I come from, it means "able to be brought (or brought back to) to a state of goodness/rightness/acceptedness." It doesn't mean "redeemed" implying that a person is currently good. It doesn't mean "forgiveable" implying that redemption is in the eyes of whoever's deciding whether the subject's past deeds are too evil to ever forgive.
It means, is there a chance that the person can, under any circumstances, become, through experience, through forgiveness, though conscious attempt to change or through an act of God -- an acceptable person, to the universe/God/Powers-that-be. Can he change, does whatever passes for God care enough about him to assist him with that change. Does he have the *potential* to be aware of wrongness, and regret having caused it, and wish not to cause it again?
To say that Spike is irredeemable based on any of his past actions misses the point of what redemption is. To say that Spike is irredeemable (on his own, though not by act-of-god) because he has shown no sign of remorse for any of his crimes, implying that he has no ability to feel such -- was a valid argument, though not a proven one -- until this episode.
Wherein he *did* show remorse. The question is not what the crime was, how forgivable any particular viewer finds it, whether it was worse than any of his past crimes, whether he meant to harm, whether he's seriously disturbed, even whether *Buffy* forgives him. It is, does he show the capacity for change? And yes, imho, he does. Did it take something awful for him to finally experience (but not yet understand) guilt and remorse? Yes. But *has* he experienced it? I think so. Think he still is experiencing it. Does his attempt to deny that make it less real? No.
I think many people are confusing -- or perhaps purposely replacing -- "redeemable" with "Forgiveable in my eyes" or with "already redeemed."
Worth precisely $0.02.