Which religious leader's endorsement created the largest single-year sales increase for a religious text in the 21st century?

Religious texts represent some of the most published and distributed products in human history. Behind these spiritual works lies a fascinating business ecosystem with unique marketing challenges and opportunities. This trivia poll explores how religious publishers have leveraged brand ambassadors to increase the reach and impact of philosophical and spiritual texts in the modern marketplace.

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Pope Francis's promotion of the Catholic Youth Catechism in 2013
Oprah Winfrey's endorsement of Eckhart Tolle's 'A New Earth' in 2008
Dalai Lama's recommendation of 'The Art of Happiness' anniversary edition in 2009
Joel Osteen's promotion of 'The Purpose Driven Life' special edition in 2012