Definition (Wilson): The process whereby religious beliefs, practices and institutions lose social significance.

Church attendance went from 40% in the mid-19th century to 10-15% by the 1960s.

The English Church Census has shown that attendances for large religious organisations has declined.

In 1971, 60% of wedding were in a church but by 2012 it decreased to 30%.

Number of Catholic priests fell by a third between 1965 and 2011.

Weber:

• Rationalisation: People start rationalising life thus undermining the religious worldview of the Middle Ages.
• Disenchantment: The Protestant Reformation started to see God as the creator of life but he didn't interfere with what went on with it.
  

Bruce: Argues that a technological worldview has replaced religious explanations of why supernatural things happen. Has greatly reduced the scope for religious explanations.

Parsons:

• Structural differentiation: A process of specialisation which has occurred with the development of industrial society. Religion has become smaller with industrialisation and more of a specialised institution.
• Disengagement: Where the functions of religion are transferred to other institutions.

Criticism: Some religious communities are "imagined communities" that interact through the use of global media.

Religious diversity (Berger):

• Scared canopy: Catholic Church = monopoly (Middle Ages). Protestant Reformation = different versions of the truth. thus more plurality of life worlds.
• Plausibility structure: Diversity undermines religion's "plausibility structure", the reasons why people find it believable. Religious belief become relative instead of absolute.

Criticism: Beckford agrees with the idea that religious diversity will lead to some questions or abandonment of their religious beliefs.