One increasing purpose

This book has a religious theme and sometimes strange grammar. Three brothers Paris are at the centre of the story. The youngest, Sim, has been in the front line of WWI and is convinced his highly improbable survival means he has a holy purpose, and the story is of his eventually successful search for that purpose. A <a href=http://answers.com/topic/one-increasing-purpose>film</a> was made of the book in 1927.