When you were younger and were watching Spongebob episodes you only knew that Spongebob is the happiest character, Squidward is the grumpiest, and Sandy is the smartest in Bikini Bottom. But as you get older, many theories suggest that the characters from the show were based on the seven deadly sins. It may sound strange but when you look at every main character it seems the theory is plausible.
Spongebob represents lust, Patrick is sloth, Gary is gluttony, Mr. Krabs represents greed, Squidward is wrath, Sandy is pride, and Plankton is envy. This theory has not yet validated by the show but still, it seems possible. It will always depend on you if you are going to believe it or not.