Do not be misled by erroneous media reports that the Scout Association is going to "welcome" atheists. This is what the Assoc is actually saying to its members (from an email): "Please be aware that you may see media coverage tomorrow focused on the part of the survey that asks about providing an alternative version of the Promise for potential members who may be atheists or are unable to make the existing commitment. The survey is broader than this specific issue but it is the topic that the media are most likely to be interested in.
No matter what the outcome of the consultation, the existing Scout Promise and its alternatives will continue to be used."
So the promise will still require people to promise duty to god. Doesn't sound like a welcome to atheists to me.