Salvation Part 2...Finding Salvation
Possibly Oothoon and Theotormon are not really characters but rather symbols of everything which prevents us from finding salvation. I mean, they had a pretty bad go of it, and held a grudge and jealous nature for a lot longer than most would (and for a much unclearer reason) so perhaps they are not individuals but rather like a montage of ALL THE DIFFERENT inhibitions (rolled together) which Blake sees as in our way.
Perhaps therefore Blake is not saying if you do all of this you will not find salvation, but in fact it is more along the lines of "this is what inhibits us" and this is what you do not what to be...so take what you've learnt and DON'T EMPLOY it!