What do theologians study about?
The theologist Thomas Altizer studied a lot about Nothing in this book:-
Godhead and the Nothing
While there are innumerable names of God in our languages,
mythologies, and traditions, we now know that there is no possibility
whatsoever of reconciling these into a common name of God, or a
universal image of God, or a universal concept of God. ...
To actually or fully to speak of God in our world is to evoke a wholly
mysterious, or vacuous, or annihilating presence. And what is most
manifestly missing in our world is an actual pronunciation of the name
of God in a genuine moment of affirmation, or in a full moment of life
and energy and body, or in a moment when we are truly awake.
Now it is true that a genuinely mystical naming of God has inevitably
been a naming of mystery, and the deeper the mystical naming the
deeper the evocation of nothingness, dark night, and abyss, so that a
mystical naming of God is finally a calling forth of unknowing, and
the deepest possible unknowing, or the deepest possible silence. ...
All too significantly no such nothingness is actually known in any
Western theological tradition, and while it has at least indirectly
entered a uniquely modern Christian theology, it has never done so
fully or decisively, and this despite its deep impact upon both
Kierkegaard and Heidegger, to say nothing of Hegel, Schelling, and
Nietzsche. So, too, an absolute nothingness has been deeply and
comprehensively envisioned by Blake, Goethe, Dostoyevsky, and
Mallarmé, just as it has purely and even totally been called forth by
Joyce, Kafka, Stevens, and Beckett. Yet it has not yet been
theologically understood, and not yet fully confronted theologically,
and this despite the fact that those thinkers and visionaries who most
fully engaged an absolute nothingness thereby clearly established
truly new theological horizons.