The problem with moderate belief

Many atheists will tell you that what people believe privately is their own business and that as long as religious ideas are not enshrined in law, a constitution or taught in schools as “science” there is no harm in it.
I agree with this stance up to a point and will not proselytise atheism to individuals who don’t otherwise expose themselves to the argument.
However I cannot help feeling slightly disappointed when someone who is in all other respects rational and intelligent turns out to be a theist. While I respect their right to believe, I can’t respect the belief itself and in some small way my respect for the individual is diminished.
The fact is that most theists (usually Christians in the U.K) are extremely moderate in their take on religion, even those who regularly attend churches. They apply religion to their lives gently, are usually ecumenical and are quietly tolerant of non-believers. Quite reasonably then they don’t understand why atheists like myself should care that these beliefs are prevalent in society.
My issue with such apparently benign religion though is the more sinister edifice it supports.
Unfortunately as we know, religion is not universally moderate and tolerant. In the U.S in particular the Christian right has a transparent political agenda. It wants to redefine America as a Christian nation, with fundamental Christian ideology at its social centre and seeks to influence the legislature accordingly.
This is not quite so evident in the U.K as yet, but the recent visit from Pope Benedict XVI gave cause for a variety of political sources to claim a greater role for faith in British society. For example Conservative party chair Lady Warsi said

the Labour government appeared to have viewed religion as essentially a rather quaint relic of our pre-industrial history. They were also too suspicious of faith's potential for contributing to society - behind every faith-based charity, they sensed the whiff of conversion and exclusivity and because of these prejudices they didn't create policies to unleash the positive power of faith in our society.

Warsi, a Muslim so moderate as to have been branded “not a true Muslim” by some exemplifies the problem. All the time enough people accept that religion is unassailably a force for good in society the greater acceptance there is for less moderate religious views. When politicians reinforce the idea it becomes more dangerous still.
There is a sliding scale of religious ideology that goes from “live and let live” to rabid intolerance of anything that does not conform to the dogma.
Not all Muslims are suicide bombers and not all Christians are homophobic creationist wingnuts. But those that are float on a buoyant sea of moderate belief that supports by degrees a more extreme agenda.
As an atheist and a humanist, I know that those of moderate faith can and would be just as tolerant, civically minded, loving and caring without religion as with it. By persuading such people to abandon irrational belief we can pull the rug from under the feet those who use the faux respectability of religion to justify bigotry, mayhem and violence.