Apparently, the Scout oath ("do my best for God and country," or, across the pond, "God and the Queen") bothers them.
Actually, they are bothered by the fact that all Scouts are required to say the oath, whether or not they believe in God. And further, by the fact that the Scouts will make exceptions allowing Muslims to mention Allah, Buddhists to mention the Dharma, but will not make an exception allowing atheists to remain silent. And -- perhaps centrally -- they are bothered that the Scouting website calls the movement "inclusive," even though it apparently excludes those with a strong objection to God.
Let it be said that the atheists, represented here by the British Humanist Association and National Secular Society, have at least half a case. To call yourself "inclusive" when you aren't sounds misleading, doesn't it? Except, of course, that "inclusive" isn't the same as "all-inclusive." For example, many churches call themselves inclusive, by which they are usually hinting that they welcome gay people or racial minorities or somebody else who often feels excluded. But they are still churches. A Hindu is welcome to visit, but can't very well join and remain a Hindu.
Strangely enough, the British Humanist Association has a similar rule. I consider myself a pretty typical Christian Humanist, of the Erasmian variety. (We pretty much invented the concept, generations before anybody thought to secularize it.) But so far as I can tell, the BHA's definition of "humanism" extends only to secular humanists. And while, according to their website they welcome "those who are not [secular] humanists but who support our aims for society and who wish to contribute and stay in touch," they will not extend to us the full privileges of membership, specifically including a vote in their affairs. That is to say, they will "welcome" those of different opinions than their own, to the extent of accepting our filthy theist money, but invite us to keep our opinions separate but equal.
Sort of like letting the atheist kid come on your camping trip, even if he can't wear your neckerchief.
Oh, and another thing: I was going to suggest that, instead of pissing on the Scouts, the secular types might consider starting their own camping club. Then I learned that they had, since 1925 -- the UK's Woodcraft Folk. They don't wear uniforms, just lookalike sweatshirts. Nobody much joins, because, frankly, it looks lame next to those snappy Scout uniforms and merit badges.