Religion is some kind of a marker. Belief, tradition, gullibility - you will have your own terms. The change in religious beliefs in Wales over the last decade has been nothing short of seismic, as can be seen from the above charts. The 2011 census was taken before the Church of England's vote on women bishops, in case you were wondering.
I won't suggest that you add 'Religious belief not stated' to the 'No religion' numbers, but Christianity has taken a heavy fall no matter how you look at it.
The statistics put Wales ahead of (or behind depending on your viewpoint) the rest of the countries of the UK as they currently stand for non-religious percentages. From a land of churches and chapels, of revivals and Sunday school outings, this is a staggering shift of world view. You don't have to be a statistician to see that, should the trend continue, Christianity will soon be a minority.
Source: Office for National Statistics licensed under the Open Government Licence v. 1.0.