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.
Edit
However, Tâo is more like negative theology, i.e. "The name that can be named is not the enduring and unchanging name."