With his usual incisiveness, Os Guinness goes past your superficial understanding to the very heart of what calling means. Far bigger than you job, deeper than your personal accomplishments, higher that you wildest ideas of self-fulfillment, calling addresses the very essence of your existence.

The hour is critical. The American republic is suffering its gravest crisis since the Civil War. Conflicts, hostility, and incivility now threaten to tear the country apart. Competing visions have led to a dangerous moment of cultural self-destruction. This is no longer politics as usual, but an era of political warfare where our enemies are not foreign adversaries, but our fellow citizens. Yet the roots of the crisis are deeper than many realize. Os Guinness argues that we face a fundamental crisis of freedom, as America's genius for freedom has become her Achilles' heel.

In 1968, at the climax of the '60s, Os Guinness visited the United States for the first time. There he was struck by an impression he’d already felt in England and elsewhere: Beneath all the idealism and struggle for freedom was a growing disillusionment and loss of meaning. “Underneath the efforts of a generation”, he wrote, “lay dust”. Even more troubling, Christians seemed uninformed about the cultural shifts and ill-equipped to respond. Guinness took on these concerns by writing his first book, The Dust of Death.

In the post-Christian context, public life has become markedly more secular and private life infinitely more diverse. Yet many Christians still rely on cookie-cutter approaches to evangelism and apologetics. Most of these methods assume that people are open to, interested in, and needy for spiritual insight when increasingly most people are not. The urgent need, then, is the capacity to persuade - to make a convincing case for the Gospel to people who are not interested in it.

What is life all about? What are we here for? Is there any meaning or purpose to our existence? Thinkers throughout the centuries have pondered these questions. While the distractions of the modern world prevent many from grappling seriously with such matters, the truth is that humans cannot live without meaning any more than we can live without breathing or eating. Os Guinness invites us to examine our lives and join the great quest for meaning and a life well lived.

The church in the West is at a critical moment. While the Gospel is exploding throughout the global South, Western civilization faces militant assaults from aggressive secularism and radical Islam. Will the church resist the seductive shaping power of advanced modernity? More than ever Christians must resist the negative cultural forces of our day with fortitude and winsomeness. What is needed is followers of Christ who are willing to face reality without flinching and respond with a faithfulness that is unwavering.

Revolution? Oligarchy? Or homecoming? Americans are approaching a "zero hour" for the republic and its distinctive view of ordered freedom. America is caught between two revolutions and alternately suppresses and squanders freedom with a prodigal carelessness, with little understanding of the responsibilities that freedom requires. Os Guinness warns that if America abandons its distinctive ideals and ideas, we will have carved into the chronicles of history yet another example of the failure of a free society.

Life is short, and it can be as easily wasted as lived to the full. In the midst of our harried modern world, how do we make the most of life and the time we have? In these fast and superficial times, Os Guinness calls us to consequential living. In strong contrast to both Eastern and secularist views of time, he reorients our very notion of history, not as cyclical nor as meaningless, but as linear and purposeful. In the Judeo-Christian tradition, time and history are meaningful, and human beings have agency to live with freedom and consequence in partnership with God.

In these stormy times, loud voices from all fronts call for revolution and change. But what kind of revolution brings true freedom to both society and the human soul? Cultural observer Os Guinness explores the nature of revolutionary faith, contrasting between secular revolutions such as the French Revolution and the faith-led revolution of ancient Israel.

In a work world that is increasingly competitive and insecure, people often have nagging questions: Why am I doing this work? Why is it so hard? And is there anything I can do about it? Tim Keller, pastor of New York's Redeemer Presbyterian Church and New York Times best-selling author of The Reason for God, has taught and counseled students, young professionals, and senior leaders on the subject of work and calling for more than 20 years.