If we were "immune" to radiation that would mean that we could become invisible, since we are visible due to our bodies reacting with radiation in the optical band. Maybe if we were X-Men lol.
Radiation has various effects. Microwave radiation excites water molecules causing them to boil (and our bodies are about 60% water...). Ultraviolet radiation destroys cells by breaking molecular bonds. Higher energy radiation (x-ray and gamma) tends to be ionizing (it causes atoms and molecules to lose electrons), and can destroy DNA.
While you may be able to affect your body's healing process, as well as avoid dangerous radiation exposure with the aid of your intuition, once exposed I don't think that your beliefs would make you "immune."