Religion's "Oneness" & Reformation's Shift

Hi all,

I've been working my way through a fascinating book ("From Dawn to Decadence: 500 Years of Western Cultural Life"[1]) and have come across a religious concept I thought might make for good discussion.
[INDENT]Applicability: Primarily applies to those religions who are monotheistic in orientation; however, could apply to many theological systems.

Underlying Religious Concept: "Strength in Numbers" and religious/theological 'comfort'. For those things 'unsure', conceptual and close to ones' heart there is comfort, affirmation and strength to be gained when others share your view; the more the better, the more who 'think like me' or agree with my view the more my comfort increases.

Background: For Christianity in Western Culture, the reformation sparked in the 16th century represented a large-scale shift from the papacy of Rome. The financial and practical burdens imposed by medieval Catholicism were great. This, along with many other factors led to the 'fragmentation' of religious views all over Europe and the Americas. Although my example, quotes and experience is centered in judeo-christian theology, the above 'Underlying Religious Concept' could well apply to many theological perspectives.
[/INDENT]Quote [1]: In illustrating this mental 'shift', and trying to understand the mindset prevailing during 'The Reformation', this author says:
[INDENT]"What makes it hard to recapture the quality of religious beliefs in the 16C is that so much has happened since to draw the human mind and heart away from the goal of saving one's soul. The meaning of faith has changed, its native quantity has been divided, its quality diluted. People blithely speak of someone's (or their own) religious preference - as if it were something like a taste in food or sport... When faith loses its singleness, its central role in life fades away, and with it the feeling that comes from knowing one's view of the world is universally shared"
[/INDENT]
Questions:

• Such overwhelming religious diversity in the world seems to suggest some measure of theological 'relativity'. Do you feel this way?
  
• To what extent does a "no one's wrong" or "Its just a preference"-notion affect the theist's strength of conviction? Do you feel this has a diluting effect?
  
• We see, every day, the subtle (and sometimes not-so-subtle) frictions caused by difference in theological thought. Could some of the evils of the world and history, often blamed on Religion, be more due to interpersonal friction stemming from "diversity of thought"?
  
• How might one justify a hard-wired religious belief system, with so many of the world's people believing differently? In otherwords, is this "dilluting" effect avoidable?
  

I thought this a good subject to toss out. Being an atheist, I'm a bit "outside" religiosity but nonetheless find it a fascinating and insightful aspect of humanity. I'd love to hear any musings anyone might have.

Thanks

~~~~~~~~~~~~~~~~~~~
[1] "From Dawn to Decadance: 500 Years of Western Cultural Life", Jacques Barzun, ISBN: 0-06-092883-2, (C)2000 Harper Collins Publishing