Deere was reared in Ft. Worth, Texas, the oldest of four children. When Jack was twelve years old, his father unexpectedly took his own life. The sorrow and great impact of this loss (which included great financial strain on the family) impelled him at first to be a rebel for a time, but then at age 17 to begin a relationship with Jesus Christ. The profound change in him revealed a bent toward scholarship, so he attended Texas Christian University in Fort Worth, where he majored in Philosophy. While there, he started working with the ministry of Young Life, leading high school students to the Lord.