I subscribe to panentheism, which means God is everything and then some. God contains all things but is contained by nothing. The “then some” for me is suggested by things like truth and beauty. Truth and beauty are real; they exist in the natural world, but they are not exactly material. (Here is a link to a nice discussion about panentheism by two of the people who introduced the idea to me.)
This notion is linked to the more common God-is-everywhere notion. Augustine broaches this topic when asking how to call to God. He writes,
And how shall I call upon my God — my God and my Lord? For when I call on him I ask him to come into me. And what place is there in me into which my God can come? How could God, the God who made both heaven and earth, come into me? Is there anything in me, O Lord my God, that can contain thee? Do even the heaven and the earth, which thou hast made, and in which thou didst make me, contain thee? Is it possible that, since without thee nothing would be which does exist, thou didst make it so that whatever exists has some capacity to receive thee? . . . Where do I call thee to, when I am already in thee? Or from whence wouldst thou come into me? Where, beyond heaven and earth, could I go that there my God might come to me — he who hath said, ‘I fill heaven and earth’?
Turning specifically to the notion of containing all but contained by none, “Since, then, thou dost fill the heaven and earth, do they contain thee? Or, dost thou fill and overflow them, because they cannot contain thee?” Of course, the entire Confession is directed toward God in a way that seems most in line with supernatural theism. And Augstine’s inquiry seems to be driven by an effort to be rigorous. Still, I find it interesting.