One aspect of beginner's mind, as I see it, has to do with what was mentioned about Stephen Batchelor's observations about the Four Noble Truths. That they are not truths to be "believed" but rather to be
understood etc etc.
When any path, any faith, is simply a collection of truths proclaimed/believed in, then "faith" fights "faith", and when "truths" other than our own are heard they are rejected as simply wrong, misguided. Why? They are not ours!
Yet if seen as demanding understanding and initiating authentic, committed practice, experience will follow. Just as when the fish trap has caught the fish, the trap is forgotten, simplicity follows. (It was at the level of
experience that Thomas Merton saw the possibility of the meeting of Faiths.)
The alternative, simply "believing" because a book or a God is thought of as demanding it, the mind then simply accumulates sets of propositions, builds up hosts of supporting facts and "proofs" of the beliefs held; in sum becomes a mind composed of a whole jumble of virtually useless "facts", identified with, "justifying" oneself. A mind so full that eventually anything new has very little chance of getting in.
(I'm sure Sky could have said all this in far fewer words...
)