After graduating high school, he attended the Moody Bible Institute in Chicago but had to drop out twice for financial reasons. He turned to professional cartooning, illustrating such strips as Bugs Bunny and Alley Oop, to help pay the bills.

When the art director for a newspaper syndicate in Cleveland offered him a job writing and illustrating his own detective strip in the late 1930s, Hamm was torn between his dream of having his own strip and his sacred calling to the ministry. After a prayer walk along Lake Erie and consulting with his bride of only a few months, Dorisnel, he resigned from the funny papers to come to Baylor to study theology.

It took Hamm 13 years to get his degree because of interruptions for military service and other factors. He taught cartooning and caricature during the 1942 winter semester. He drew for the Baylor Round-Up yearbook from 1945 through 1948. After graduation in 1948, he taught commercial art classes at Baylor and later served as the art departments interim chairman.

The minister-in-training was known for giving chalk talks, or illustrated sermons, at Waco area churches throughout the 1940s and �50s. Hamm realized that combining preaching with illustrating was his ministry.

Expanding his reach 
In the 1960s, he and his wife founded the syndicate Religious Drawings Inc. in Dallas to distribute his inspirational artwork to newspapers around the globe. At one point, his cartoons reached a congregation of 29 million readers a week.