Final answer:
The evangelist Saint Paul often compared the Christian life to a race to encourage discipline and purposeful living in faith.
Step-by-step explanation:
The evangelist who often compared the Christian life to a race is Saint Paul. He is not one of the four traditional authors of the Gospels (Matthew, Mark, Luke, and John) but he wrote numerous letters (epistles) in the New Testament that contain this metaphor.
For example, in 1 Corinthians 9:24, Paul says, "Do you not know that in a race all the runners run, but only one gets the prize? Run in such a way as to get the prize." This metaphor is used to encourage Christians to live their lives with purpose and discipline, as athletes do when training and competing.