Though formless Brahman is one of aspects of Advaita it is more of philosophy than a Theology. Theists consider Brahman of Sankaracharya as God. But from an Aethistic point of view Brahman is Universe itself. (read "Bhagavathgeeta & Big bang). Another main teaching of Advaita is that Mukthi is acheived only by Jnana. Also another teaching of Advaita is Maaya which explains how humans are deceived by illusion.
