Within the Judeo-Christian Tradition there are differing concepts of God – ideas range from St. Anselm’s ‘that which no greater can be conceived,’ to the more apophatic (more on that term in a minute) ideas of Judaism and Eastern Orthodoxy – that we cannot know what God is, only what He is not.
Apophatic theology is also called ‘negative’ theology, in that it doesn’t seek to ascribe positive aspects to God in His essence; God is completely and totally beyond anything mankind could ever grasp. Passages of Scripture such as 1 Kings 19:11-13, Exodus 3:1-21, John 1:18, and St. Paul’s statement in 1 Tim. 6:15-16 all indicate a total other-ness that God has as well as the unbridgeable gap between God and humanity. The apophatic tradition also has strong roots in the Early Church fathers as well – St. Cyril of Jerusalem, Tetrullian and the Cappodician Fathers ( Basil the Great, Gregory of Nyssa and Gregory of Nazianzus ) are all apophatic in their theology. Apophatic theology was prominent in the thought of St. Thomas Aquinas and in the writings of various other medieval figures such as Meister Eckhart and St. John of the Cross, and is standard in the theology of the Eastern Orthodox Church today.
Any direct, positive statement about God are only those which are revealed – for example, the Trinitarian nature of God, God’s love, compassion, and other attributes. These are revealed to humanity by God through Scripture and in the person of Jesus Christ – it is only through what is revealed that we can make any kind of positive statement about God.