The Seven Deadly Sins were a group of powerful magical beings who were known for their malignant ways, which embodied the worst characteristics of human nature. They were parasitic beings who fed off of the evil that was around them, mistakenly being attributed to causing evil.
Although not the exact source of evil, the beings that came to be the Seven Deadly Sins were one of the biggest factors contributing to it. They were imprisoned in the box and freed, albeit accidentally, by Pandora at 8000 B.C.E. The Sins proceeded to label Pandora their "mother", as she was instrumental in their freedom.
Upon attacking Kahndaq, the Seven Deadly Sins were taken down by Black Adam. They were subsequently easily imprisoned by Adam, though they were well aware of the champion's later villainous turn but nonetheless feared him greatly.
In the 21st Century, upon being found by Dr. Sivana, the Sins allied with Adam in recreating the world. The Sins' first task was to find the worst soul in Philadelphia, whom they proceeded to possess and make a giant monster. The Sins abandoned their duty after Adam was defeated by Shazam. It was later that year that the Seven Deadly Sins numbered "six" after Pandora killed Envy.