The Goddess had collected 30 cosmic cubes. With some of this power she was able to put some of Earth's heroes into a form of telepathic trance that appealed to their own religious beliefs. The Goddess claimed to rid the universe of evil and selected only those she deemed worthy.
The Holy Guard was created when Goddess took the 30 cosmic cubes and combined them into one force, known as the Cosmic Egg. With it's power the Goddess could create a group consciousness throughout the universe to those she deemed worthy. While she did this she needed protection from them. She also meant that they destroy the true non-believers, in some cases their family and friends. They all believed they were working for the greater good. This begins the Infinity Crusade. She created a base of operations for the Guard, a cathedral on a planet she made known as Paradise Omega.
Moondragon was made the high priestess of the group, keeping in contact with the Goddess at all times and coordinating the defenses of Paradise Omega. The amount of control over other members of the Guard varies. The Silver Surfer and Thor were able to resist her and break control from her. Storm still believed in the compassion of the Goddess, but did not want to commit murders for her. Others, such as Wonder Man, Captain America and US Agent all experienced the loss of their morals, making them willing to kill their opponents.
The remaining heroes of Earth travelled to Paradise Omega in order to stop the Goddess. For the most part, the Holy Guard proved to be the victors. When Adam Warlock created the illusion of the universe's destruction, which was the Goddess' true intent, the Holy Guard saw this and broke their beliefs in the Goddess as good in nature. This was the end of the Guard.
Most members of the Guard experienced a sense of guilt for their controlled actions, most notably Storm and Moondragon, who felt used.