Apophatic theology, from Greek apophasis, denial, holds that God transcends every name and concept and is best approached by negation: not this, not that. Its classic Christian source is Dionysius the Areopagite’s Mystical Theology. Similar ways are found in Neoplatonism, Vedānta, Jewish and Islamic thought.
Apophatic theology
The negative way: speaking of God by denying all that God is not, since God is beyond every concept.
Also: via negativa, negative theology