Marion's theistic phenomenology should pose hardly any problem, judging by this book summary:-
God Without Being, by Jean-Luc Marion
Jean-Luc Marion is one of the world’s foremost philosophers of
religion as well as one of the leading Catholic thinkers of modern
times. In God Without Being, Marion challenges a fundamental premise
of traditional philosophy, theology, and metaphysics: that God, before
all else, must be. Taking a characteristically postmodern stance and
engaging in passionate dialogue with Heidegger, he locates a “God
without Being” in the realm of agape, or Christian charity and love.
If God is love, Marion contends, then God loves before he actually is.
Such a reading should re-locate your object of atheistic unbelief to a more conceivable place, although it won't stop you disagreeing with most of the theists you previously disagreed with. It's the development of a more useful, nuanced and uncommon view. Nevertheless, you may find it a self-emptying concept, like the Gateless Gate or even Tâo.
However, Tâo is more like negative theology, i.e. "The name that can be named is not the enduring and unchanging name."