The Galactic Army of Light was a terrorist organization commanded by the Vulcan Sybok, made up of inhabitants from the planet Nimbus III. Members were recruited by Sybok by mental manipulation, as he was capable of relieving the secret pain he believed every man possessed. In 2287, the Galactic Army of Light managed to take Paradise City and taking hostage the three ambassadors from the Federation, the Klingon Empire, and the Romulan Star Empire stationed there.
This however was only a means to an end, as they used it to successfully lure the USS Enterprise NCC-1701-A to Nimbus III, and subsequently commandeered the ship in order to penetrate the Great Barrier surrounding the center of the galaxy. Taking the Enterprise through the barrier, Sybok was able to make contact with an entity whom he believed to be God himself, although it was later learned that it was not God, but rather a malevolent alien whom had manipulated Sybok into bringing him a space vessel. (Star Trek V: The Final Frontier)