God is a pure spirit. As God has no body, when we speak of His eyes and His hands we only speak in a figurative manner, in order to make ourselves more understandable according to our human way of speaking. Yet God has often taken on visible forms, in order to be seen by men. Thus he showed Himself in the form of a dove at the baptism of Jesus, and in the form of tongues of fire on Pentecost. Angels and devils are pure spirits.
Men are only partly spiritual, because they have a body.
Man's soul is a spirit, absolutely independent of matter, and by creatures indestructible. By his free will man can even defy his Creator, God. When we say that God is self-existing we mean that He does not owe His existence to any other being. He exists of Himself, deriving His Being from no other. God is the First Cause.