The Walking Dead often shows a bleak view of humanity in an apocalyptic situation. Many characters have expressed a lack of faith.

Hershel (Scott Wilson) was extremely devout when first introduced, and though his faith gets shifted throughout the rest of his tenure, it does not dissolve. In the episode Beside the Dying Fire, he mentions being Christian and states, “I can’t profess to understand God’s plan. Christ promised the Resurrection of the Dead. I just thought He had something a little different in mind.”

Rick Grimes (Andrew Lincoln) asks for God’s guidance at a church in the Season two episode What Lies Ahead, though professes he’s never been much of a believer. That would imply a lack of faith pre-apocalypse. His son Carl (Chandler Riggs) has rather obviously, though not directly, admitted to atheism around that same point in the story. Carol (Melissa McBride) is also seen praying that they find her missing daughter, Sophia.

As the story progresses, these types of requests to the above stop happening. The characters harden. When they eventually find Father Gabriel (Seth Gilliam, a man who shows more abhorrent characteristics than righteous ones), thr group shows no sign of interest in his possible ability to guide them as a religious man.

But these character shifts are not evidence of an atheistic agenda, they’re merely the product of our characters living and surviving in this world. They’ve reached the point where they have stopped requesting the help of God to survive. In a way, their religion has shifted to a belief in their group as a family and its ability to keep them alive. Each character internalizes their religious beliefs and holds onto them differently.