Sunyata is the concept of emptiness behind the things - its the idea that there is no individual soul and no world soul. Nirvana is in you, and Nirvana is in the world, Nirvana is in everything, Nirvana is Samsara and Samsara is Nirvana.
Thus, if you look at the theological definitions of God: he is immanent and transcendent, he is pure being, the core form of existence. Every thing in the world exists. God - in this understanding - is part of everything. But if we say that things exists we have an concrete understanding of these things, we have definitions, ideas and concepts. Because of this, every existence has more facettes than pure being, thats the reason why both God is in everything and transcendent, becaure pure being is different to concrete being.
To get the idea of pure being you must take off all ideas, definitions and facettes, then you will have pure being. But if you take off all these things, what is the result? It will be "Nothing". If you subtract all things from you and individuality, what is the result? yes, without your identity you will be nothing.
That is, why Being and Nothing are the Same and why Samsara is Nirvana. And why God as the purest form of existence is Nirvana.
Your identity is more than pure knowledge, that you're existing, your identity is to know that you are differently to other, that you are an individual. Thats the essence of the western left-hand path and some eastern schools.