Philadelphia was founded by William Penn, a Quaker who infused his religious values throughout the city. When choosing a name for the city, Penn was inspired by the concept of creating a place where living cohesively and peacefully with one's neighbors would be a key tenant of the community. Penn himself had experienced persecution due to his religion, and he hoped to establish a city where those issues would not be at play.

Furthermore, Penn was a Quaker, whom also call themselves "Friends," a moniker which describes the key tenants of their faith. They peacefully objected to war, wore plain clothes, and opposed slavery. These aspects of his life lead to the name "Philadelphia," which comes from the Greek philos (φίλος) meaning friendly or love and adelphos (ἀδελφός) meaning brother. So, the name that Penn gave the city literally translates to Brotherly Love.