Aum is the most powerful of all mantras. It is good to chant Aum seven or more times before and after each meditation. Chanting "Aum" puts you in harmony with the vibration of Eternity. "Aum" opens the gateway to the infinite highway of light.
AUM or Om is not related to any religion because Om was practiced before the birth of all the religions of the world.
Om (AUM) is the truth of all truths, the light of all lights and the destroyer of all illusions.