First: When the topic is the importance of the archetypal hero (Christ) or meta meme (Religious myths) in the development of healthy societal memes (like egalitarian aims) the initiators of those movements and from where the developed their world changing wisdom is pertinent to the discussion.

Scientific progress is not the subject here, you just brought that in the back door. Moral progress was the issue.

Umm. I should say here that I'm trying to sort this all out in my own mind. My 'spiritual' development is very similar to Sam's: raised secularly, philosophically curious, meditated/prayed my way into an accidental life changing transcendental experience. But I've signed up to the Christian tent as a result. I am very aware that secular humans struggle to create communities that nurture real moral action unless it has some other ideology on which it can narrowly focus.
That said, I can't avoid the issue that religiousity has not sidestepped ideology very well afaict. And when religion becomes an ideology there are catastrophic results.