The Kabbalists felt that the Divine unity was valid for each of the ten Sefirot.
That is to say:
He was Chesed (Kindness, Benevolence) as an attribute, He was the one who gave Chesed and the one who was the object of Chesed.
He was Tiferet (Beauty), the one who created it and the one who was affected by it, and so on.
God was all the aspects of Divine manifestation.
There was nothing in revelation that could be said to be out of the Divine.
He was in all and all was in Him.
Which is what is sometimes called Lower Unity.
It exists in the world below, in time and space.
The Higher Unity, defined by "there is nothing besides Him", is a nullification of all reality, which is the very opposite of the confirmation intrinsic to Lower Unity.
All of the above constituted, theoretically at least, one of the more outstanding differences between Chasidim and Mitnagdim.
It seems there was a tendency on the part of certain thinkers of the time to speak of a gap between God and the world, as though the Divine had to withdraw from the world in order for Creation to take place.
God was somewhere else, high up and distant.
According to the Chasidim, this was a limiting of God, because it does not matter where one places Him, high or low, inside or outside; He is limited by not being everywhere.
The argument, incidentally, deliberately uses the words of Maimonides's Thirteen Basic Principles.
Because, to be sure, the argument is not against unbelievers; it is against good Jews, men of faith, who believe in Divine providence.
Since God knows everything and nothing can add to His knowledge, then the world below is united with the higher knowledge and with the upper spheres and is not separate.
There is not, as many think, a difference between this world and a God who exists somewhere beyond in the transcendental.
God is here, insofar as His knowledge and His Being are one.
It cannot be said that this is true of man, of course, who can be in one place and think of something else, somewhere else.
But in terms of the Divine, as said, there is no distance, no gap, between consciousness and existence.
God is thus at the same time that which encompasses all the worlds and that which fills all the worlds, the transcendent and the immanent.
–Rabbi Adin Steinsaltz
From The Sustaining Utterance, p. 86, by Rabbi Adin Steinsaltz