Author Ben Smith once believed a faithful and literal interpretation of the Bible meant he would also have to believe in a universe and Earth only thousands of years old. Young-Earth proponents use the creation account in Genesis, the first book in the Bible, to estimate the Earth's age to be around six-thousand years.

While many people are content to accept this view of Earth's beginnings, other Christians struggle to reconcile the scientific evidence supporting an old Earth with the teaching of the Bible. As Smith matured in his understanding of God, the Bible, and science, he came to...