Strawman argument.
None of us (on either side of this discussion) believes that "man is his own saviour"
(at least not that I've seen from anyone in this discussion... I've not read the entire thread, however.)
If someone believes they must do something to become saved, and if they don't do that, then they won't be saved, but by
doing it, then they become saved, in effect, they then become their own saviour, don't they? Isn't that what you believe that
you must do something, like produce your own faith in Christ rather than of it being a gift? So then, how could any other interpretation be drawn?
Christ is correctly perceived as Saviour when it is realized that He does it all, we do nothing - every millimeter of it is fully and completely a gift from a merciful and gracious God with nothing remaining to be done. We are to just rest in what He had accomplished on our behalf. Everything we might attempt to do to complete it is in effect actually saying that Jesus's offering was incomplete as it stands, and that we must do something to close the circle (so to speak).
It can't be both ways. Either we must do something, no matter how slight to acquire it, in which case we've saved ourselves, or, we rest trusting entirely in what Christ did. The latter is the correct answer.