I'm quite certain the reduction of practising Catholics isn't down to science.
The rest are just comfortable western middle class people who regardless of science probably wouldn't be bothered with religion simply because it gets in the way of their lifestyles.
Is there a large increase of Muslims becoming atheists or non practising Muslims?
This is what has happened in the western world when religions have been immersed in scandals or crimes.
People either lost their faith or walked away from the churches.
Is this a big thing in the Islamic world?