Celebration of being unconquered by superstition and consistency in the pursuit and sharing of knowledge
The cult of Sol existed within Rome since its early days as a republic, and Invictus was an epithet used for Jupiter, Mars, and Apollo (among others). The festival celebrated these gods and may have also been used to celebrate the winter solstice, though this is debatable.
The Satanic Temple Colorado Congregation typically celebrates this holiday privately as we are usually still recovering from Saturnalia.
Past Sol Invictus