For surveys of the religious landscape in the UK and America see:

NatCen (2015) ‘NatCen’s British Social Attitudes survey: Change in religious affiliation among adults in Great Britain’
https://www.natcen.ac.uk/media/893167/religious-affiliation-britishsocial-attitudes.pdf

Commission on Religion and Belief in British Public Life (2015), Living With Difference: Community, Diversity and the Common Good, The Woolf Institute
https://corablivingwithdifference.files.wordpress.com/2015/12/living-with-difference-online.pdf

Pew Research Center (2015a), ‘U.S. Public Becoming Less Religious’
http://www.pewforum.org/2015/11/03/u-s-public-becoming-less-religious/

Pew Research Center (2015b), ‘7 key changes in the global religious landscape’
http://www.pewresearch.org/fact-tank/2015/04/02/7-key-changes-in-the-global-religious-landscape/

For a discussion of the relationship between religion and politics from a leading UK politician see:

Brown, G. (2011), ‘Faith in Politics? Lecture by Gordon Brown’
http://rowanwilliams.archbishopofcanterbury.org/articles.php/903/faith-in-politics-lecture-by-gordon-brown

For a useful short discussion of the nature of religious fundamentalism see:

Ruthven, M. (2007), Religious Fundamentalism: A Very Short Introduction. Oxford: Oxford University Press

Armstrong, K. (2005), ‘What is Fundamentalism?’, LSE.
http://www.lse.ac.uk/publicEvents/pdf/20050126-Intolerance-Armstrong.pdf

On radicalisation and extremism, useful documents are:

Religious fundamentalism and radicalisation – Briefing from the European Parliamentary Research Service
http://www.europarl.europa.eu/RegData/etudes/BRIE/2015/551342/EPRS_BRI(2015)551342_EN.pdf

HM Government (2015), Counter-Extremism Strategy
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/470088/51859_Cm9148_Accessible.pdf.