In his new book, Convictions: How I Learned What Matters Most (HarperOne, May), biblical scholar Marcus J. Borg (Meeting Jesus Again for the First Time) reflects on the events in his life that shaped his faith and his convictions about the future of American Christianity. PW spoke with Borg from his home in Portland, Oregon.

What prompted you to write this book?

My birthday always falls during Lent, but two years ago, when I turned 70, my birthday fell on a Sunday in Lent. The idea for the book grew out of preparing the sermon I was going to preach that day at Trinity Episcopal Cathedral in Portland, my home church. The combination of Lent being a season of mortality and my turning 70—the main character in one of John Updike's last novels reflects that half of American men who live to the age of 70 do not live to 80—led me to reflect on what matters most to me and on my own convictions, those settled ways of seeing that are not easily shaken. I develop this into a deeper reflection upon a triad of memories, conversions, and convictions: Memories of absorbing certain religious and political beliefs as I grew up; conversions, or the major changes those beliefs (such as belief in the Bible as the literal word of God); and convictions, such as the centrality of social justice as a bedrock biblical teaching.

How did you come up with the title?

My working title was What I Wish Every American Christian Knew. American Christianity is deeply divided; the most visible division is between the Christian political right and the Christian left. For the right, morality tends to be about what I call "loin issues"—sexual morality—and polls have also shown that the more frequently people attend church, the more likely they are to be pro-war, pro-life, or to support gun rights. For me it's embarrassing that the most visible face of American Christianity is reprehensible. I've often said that the greatest obstacle to Christian evangelism is Christian evangelism itself.

How have you changed over the years?

I've moved from a faith I acquired by osmosis as a child, through a period of skepticism, to a set of convictions that I own with great passion.

Will readers be surprised by anything they learn about you in this book?

People who have read a half dozen or so of my books will likely learn very little that's new. All of this book will be surprising to people who know Christianity only at a popular level--I overturn so much of what I call common Christianity.

What lessons or insights would you like readers to take from the book?

Christianity is authentically about changing the world. God is real, and God's passion as revealed to us in Jesus is about the transformation of this world. If there's an afterlife, then it's a bonus. I do see myself as a Christian apologist. Christianity properly understood makes persuasive and compelling sense.

What's next for you?

I'm working on a second novel that's a sequel to my first, Putting Away Childish Things (HarperOne, 2010). It follows the two main characters, Martin Erickson and Kate Riley, in a new setting. I really enjoy writing, and it's a special treat to write fiction because I can make everything up.