Is there a work from John Steinbeck that does not include religion in any way?

One Steinbeck work that does not explicitly include religion is Of Mice and Men. It is wholly focused on the here and now. In it, George, Lennie, and the other ranch hands are exploited by a system that keeps them wandering from job to job, unable to put down roots or form a real community. They are not treated with dignity at the ranch, and they have to worry about what will happen to them as they age and can no longer work.
George and Lennie don't talk about God or religion and don't place their faith in a better afterlife. They dream of a better world in the present time or near future. They have a materialist vision of owning their own farm and living off the fat of the land. They dream of taking a day off when they want to and only inviting people they like to visit. This is a dream of paradise, but it owes more to the secular American Dream than to religious tradition. Even as Lennie is about to die, it is the farm dream George reminds him of, not heaven.