All I can add to this thread is that nearly all of my friends in Madrid - most of which are younger than me - it seems that religion is absent in their lives. This is only an observation and not a judgement. Most were no doubt raised as catholics but none of them, as far as I know, attend church.

From what I've heard, the Catholic churches (at least those in the cities) are becoming populated with Latinamericans which, it seems, follow more closely to the catholic religion in Spain than the Spaniards do.

Saludos, MadridMan