Sixteen year-old Matt Benson moves with Robert, his widowed father, to Boaz, Alabama for one year for Robert to conduct research on Southern Baptist Fundamentalism. Robert, a professsor of Bible History and New Testament Theology at the University of Chicago's Divinity School, enlists Matt to assist him as an undercover agent at First Baptist Church of Christ. Matt's job is to befriend the most active young person in the Church's youth group, and learn the heart and mind of teenagers growing up as Fundamental Southern Baptists. Olivia Tillman is the fifteen year old daughter of Walter Tillman, the pastor of First Baptist Church of Christ. Robert and Matt move to Boaz in July 1970, and before school begins in mid-August, Matt and Olivia become fast friends. Olivia's life is centered around her faith, her family, and her friends. She is struck with Matt and his doubts and vows to win him to Christ. Over the next year, Matt and Olivia's relationship blossoms into more than a teenage romance, despite their different religious beliefs. June 1971 and Matt's return to Chicago comes too quickly, but the two vow to never lose what they have, even promising to reunite at college in two years after Olivia graduates from high school. Girl and God is told from the perspective of past and present. The story alternates between 1970-1971, and 2017. After Matt left Boaz in June 1971, life happened and Olivia and Matt's plans fell apart. However, in December 2017, their lives crossed again, almost miraculously, and they have almost a month in Boaz to catch up on forty-six years of being apart, and to discover whether their teenage love can be rekindled and transformed into an older adult romance. In 2017, Olivia and Matt are quick to learn they are vastly different than when they were sixteen and fifteen years old, especially, when it comes to religion and faith. Will these religious differences unite them? The real issue is the secret Olivia has kept. Will Matt's discovery destroy any chance he and Olivia have of rekindling their teenage relationship?