Oneness (Eines)
- Holismus
- Nichtdualismus
- Henosis, a concept in Greek mysticism denoting "oneness" or "unity"
- Monismus, a metaphysical concept in philosophy
- Meditative absorption, oneness, Samadhi
- Divine simplicity, a theological doctrine that holds God is without parts
- Monotheismus, the belief that only one deity exists
- Tawhid, Islam's fundamental concept that God is one and single
- The three oneness, three core assertions in the Bahai-Lehren#Einheit
- Oneness Pentecostalism, a movement of nontrinitarian denominations
- Systems thinking