What is your thoughts on where the Christianity went to? Mankind and religion goes back into pre-history. Humans seem to have a gene that requires them to seek some of the items Christianity provided. Assuming that humans have not changed, there must be something that is replacing the Christianity.
My bet would be the items Christianity provide are in the forms of knowledge and history of human spirit. And I would guess the internet is giving better knowledge on the subjects in question.
Answer to the question is hidden in idioms which are common to various different languages. “God knows” can be described as “I dont know, and there is possibilty that nobody else does”. The main difference is access to knowledge, partially by easier ways than printed books.
Downsize is that we have to deal with hoaxes and quacks. Certain people - some religious, but also some well informed skeptics - are either afraid what will replace religion or are actively fightning misinformation. Clergy tend to claim that religious beliefs are either harmless or are motivating people to live healthy life without committing crimes. This would be fine, unless religious people start to create conspiracy theories of their own or fight science, or even take part in religiously motivated violence.
Science wont be new religion, but rise of various beliefs which are destructive (various sects, breatharianism) to the believers indicates risks to the society. Christian beliefs are relatively harmless, unless you live in Northern Ireland.
The headline is painting with wide strokes as the graph shows identifying as Christian is still quite common outside most of northern and western Europe. Also keep in mind that Islam will become dominant in several of the “godless” countries if demographic trends continue.
The headline is probably directed toward audience in UK, I expecteded it to be similar to France or Germany. There might be shift happenning.
When it comes to Bratislava, Slovakia where I live, situation should be similar to Portugal, but because we are culturally close to both Czech Republic and Poland it differs a lot in various regions of Slovakia. northeast of the country is very religious on similar level as Poland, southeast is more secular. 70% of secular people in my case is an informed guess.
I would expect that amount of secular people in region where I live is much higher compared to USA.