It means more than the spirituality of God, for that includes only that he must be spiritual, and, also, as we have seen, that he should be purely spiritual. But there is nothing contradictory in the idea, that created spirits might have a composite spiritual nature, composed, for example, of mind, soul and spirit, as three distinct essences, or that a spiritual nature should have a spiritual body, as well as a spiritual soul. But in God there can be no composition, and therefore his spiritual nature must be uncompounded. Even his attributes and his nature must be in such a manner one, that his attributes essentially inhere in that nature and are not capable of separation from it, which really makes them one with that nature. But this would involve destructibility, and changeableness, each of which is inconsistent with absolute perfection and necessary existence.
Composition involves a time of separate existence of the parts compounded.
If the parts have been compounded, it has been done by some force from without, or has been a growth in his nature. They have not been added from without, because God is independent, and therefore cannot be affected from without. Besides all outward form and all else than God had its origin in him, and he existed as God before it. They have not been a growth in him, for, if so, he is not unchangeable. Any such addition to God or growth in him is also inconsistent with absolute perfection and necessary existence.