Rene Descartes, probably the 17th century's most influential philosopher, is best known for his humanistic maxim, "I think, therefore I am." That led Western thought in a direction away from the biblical teaching that God thinks, therefore we are.
Russell Shorto's Descartes' Bones: A Skeletal History of the Conflict Between Faith and Reason (Doubleday, 2008) is a well-written tracing of what happened to the skull, bones, and ideas of Descartes following his death, but Shorto doesn't seem to care much about souls. John Carroll's The Wreck of Western Culture: Humanism Revisited (ISI Books, 2008) is much deeper. Descartes jump-started Europe toward 18th-century Enlightenment claims that Man via reason can ascend to the heavens and kick God downstairs to, at best, a deistic basement.
Carroll shows that the Enlightenment blew out the candles all over Europe and contributed in the long run to intellectual and emotional darkness. The 18th century was a busy one for England, as Brendan Sims narrates in another well-written book, Three Victories and a Defeat: The Rise and Fall of the First British Empire (Basic, 2008). In the long run those Enlightenment ideas turned many Anglican churches into museums or clubs, and a second British Empire lost its reason to live.