When people see significant, often religious imagery in everyday images, from grilled cheese to their dog's butt, it's called "pareidolia." But as for exactly why people see divine figures like Jesus in things like potato chips and other ordinary objects, a recent study in the journal cognition says it is due to a phenomenon called "the moral pop-out effect."
What this pop-out effect theory states is that when moral concerns are on your brain or bad things are happening to you, such as a family member being ill, you're more likely to perceive the world in a way that re-dresses injustice.
In the New York Times article on the phenomenon, the effect is compared to when you feel hungry. When you're hungry, you're apt to focus on the food around you. Smells and pictures of food "pop out" at you on the street. When you're looking for guidance related to the problems in your life, signs of salvation and morality pop out at you. So the reason you see Jesus in your potato chip is because your brain is sort of hoping to see Jesus in that potato chip.
In a series of experiment to determine the existence of this moral pop-out effect, people were quickly flashed screens of scrambled letters in which some words were formed. When "moral words" such as "virtue, steal, or God" flashed, participants identified those words over "non-moral" words. Therefore, "moral words" are more easily recognizable.
In a follow-up experiment, people read two versions of a fake news story in which a murderer was either arrested or not arrested. If the murderer in the article was still at large, participants recognized moral words even faster in the previous experiment than those who read about the murderer being brought to justice.
As for the people who see religious figures in basic images and objects, many of those reports were by people who were stressed over a family member's health. So, the next time things are looking pretty down in your life, expect your junkfood to get a lot holier!