Atheists sometimes object that there is no clear definition of a god/God. Here I want to say very clearly that God cannot be defined, God's attributes can only be described. If God is the creator of the universe, then from this it follows that before creation God was alone and that there was no one else, nothing else other than God. As universe means space, time, matter and energy, so from this it follows that before creation there was no space, no time, no matter and no energy. That means God was neither in any space nor in any time and that God could contain neither any matter nor any energy, because before creation there was no space, no time, no matter and no energy. Being neither in space nor in time God will be thus spaceless and timeless. Containing neither any matter nor any energy God will be thus immaterial and his total energy will be zero. All these directly follow from the statement that God is the creator of the universe. By simple logic it can also be shown that this God being spaceless and timeless will also have the following attributes: God will be changeless, immortal, all-pervading, one, unborn, uncreated, without any beginning, without an end, everlasting and non-composite.
Some believers also say that God is omnipotent and omniscient; he/she/it is all-powerful and all-knowing. But I do not think so. God being the creator of the universe must have necessary power and knowledge for creating it. Otherwise how has God created the universe? But I do not think that solely due to this reason God can be called omnipotent and omniscient.
Thus the complete description of the creator of the universe will be this: God is spaceless, timeless, changeless, immortal, all-pervading, one, unborn, uncreated, without any beginning, without an end, everlasting, non-composite and immaterial.
Whatever else has been said about this God is just wishful thinking.