I would interpret the phrase to mean that close-mindedness of the atheistic position makes it impossible for the atheist to entertain possibilities they may be correct under the position "God created the universe"
To an atheist, this isn't a bad thing. But in truth: Evidence that this universe does exist without any
understood reason or cause, nor lack of cause, but simply the
mystery to exist ; means a creator is still potential. And that is where an atheist is limited. An atheist chooses to accept only what they can believe relative to current technologically enhanced observation of the five senses. These same five senses lie to mankind all the time. Because: interpretation of events, are as events
'appear' to be. As defined by
individual understanding.
There is a better understanding of philosophies, and greater ability to muse philosophically: If
potential truths--concerning existing--are not ruled out just because it is impossible for our limited senses (and abilities) to unravel the nature of how existing is even possible.
But that is just my opinion... *shrug*
keep your mind from this way of enquiry, for never will you show that not-being is
~parmenides