I doubt the original signers thought that, Jackson, at least not based on what else the H III says. It seems to be more of a skeleton and is fleshed out more by the individual:
Ethical values are derived from human need and interest as tested by experience.Humanists ground values in human welfare shaped by human circumstances, interests, and concerns and extended to the global ecosystem and beyond. We are committed to treating each person as having inherent worth and dignity, and to making informed choices in a context of freedom consonant with responsibility.
The original signers were also made of those from the U.U. and Judaic Humanists too. I have a book around here from the AHA that has an even longer list of signers after 2003 from a variety of backgrounds (I’ll have to hunt it down). So, IMO, the H III is open to interpretation of the individual. I did a paper on this subject (not on my website yet), which Fred Edwords kindly read over for me. Aside from a few grammatical errors, Fred took no issues with it- not even my use of those with non-realism beliefs as an example of what the U.U. signers of the first Humanist Manifesto might have believed. What I mean by the use of those with non-realism belief as an example is that I used the Sea of Faith for that example. So in essence, the H III is open to interpretation of the individual. At least that is my take on it all given the research I have done on it and kind assistance of the AHA. I did make mention of the Humanist Manifesto 2000, but the main focus was the I, II, and III. So in reality, even those like John Shelby Spong (Jack), Don Cupitt, et al fit under the Humanist Manifesto III too. However, this could also be interpreted as “Life’s fulfillment emerges from individual participation in the service of humane ideals,” but I truly think it is more than that though. It is really interpreted broadly.
That is just my take on it all, but others may have different view of the H III and I do know others may view it differently regardless of how much study they have put into it all. I also understand Paul Kurtz probably has a completely different view too. Thus, why I say it is open to interpretation, but at the same time, if Jack wants to say “Humanism is not anti-Christian or anti-God because it is through the human that we experience The Holy The Other. The Divine is The Ultimate depth of the human”, which he says is the thesis of his current book, who am I to argue? BTW, you probably won’t see that quote anywhere, because it was via personal communication. Both Paul and Jack’s interpretations are appropriate concerning the Humanist Manifesto and neither one are excluded. So the interpretation of the H III is open to Secular, Religious, Ethical, and Christian (non-realists) Humanists.
Hopefully, that helps a little, but keep in mind, my information comes from the AHA and not from the CSH.