Why?
Well maybe more people have moved on and believe more in science?
Then again, I have a friend whose "hobby" is quantum physics. Apparently the latest theory on how the universe was formed, is that there wasn't a "big bang" but two (for want of a better word) "brains" came together and fused.
There is also the theory that there are actually 11 dimensions, but because we are stuck in 3 dimensions, we can't see the others (Just like if a paper cut out man was stuck to a piece of paper, he would only see one dimension)
Frankly after hearing this, I'd be more inclined to believe in religion! Oh come on - that idea is barking!
One thing I have noticed, is that nowadays (One religion apart) the most intolerant and unpleasant people, seem to be the atheists who want to ram their beliefs (Or should that be lack of beliefs) down everyone's throat and make everyone conform to their way of thinking. In the same breath, they accuse the religious of being intolerant and forcing their beliefs on the atheists.
Like it or not, religion of all sorts has tended to create moral behaviour amongst humans for all history. Humans are violent animals by nature - and maybe their leaders have realised early on that one way of keeping society in check is to hang over the threat of divine retribution.
No religions tend to preach "get out there and cause conflict" - it's the followers of those religions, or their leaders, who twist the religious message for their own purpose.
Churches struggle to fill their halls, the mosques though may be overflowing. What does that tell you? Many messages actually, not all obvious. One being that the Christians are lazy and don't think they need to attend organised religious worship anymore.
100 years ago the churches were packed. Were people more religious? Well, maybe no - don't forget that at that time, the churches provided most of the social activity in the towns and villages. Plenty of other things to do now.
So many reasons that say the UK appears not to be particularly religious.