Justin McClain is a teacher at Divine Mercy Academy in Pasadena, Maryland. He taught theology and Spanish at Bishop McNamara High School from 2006 to 2021. He has also served as an adjunct lecturer in Spanish for the precollege programs at the University of Maryland, College Park, and taught English as a second language at Prince George's Community College. He received a Golden Apple Award for excellence in teaching and commitment to Catholic education from the Archdiocese of Washington in 2017.

McClain is the author of several books, including Called to Teach, Alleluia to Amen, and the award-winning Called to Pray. He is a regular contributor to the National Catholic Register, Catholic Exchange, and the National Catholic Educational Association. He was a consultant to the United States Conference of Catholic Bishops' Secretariat of Cultural Diversity in the Church's Subcommittee on African-American Affairs in 2015, as well as to the USCCB's Department of Justice, Peace, and Human Development, and the Secretariat of Catholic Education, in 2018. McClain is a lay Dominican.

He lives with his wife, Bernadette, and their children in Bowie, Maryland.