A philosophical belief that there are two opposing forces in the universe that are always contending or seeking balance with each other. These can be seen in concepts of male/female, yin/yang, mind/body, god/goddess, good/evil. Some spiritual traditions accept this duality. For example some Christian traditions believe that an individual is a soul “trapped” within a body and some Pagan traditions see the highest form of the Divine in the forms of a God and a Goddess.
The opposite of dualism is monism.