"If resurrections happened every day, atheists would find a natural reason for them and still reject miracles."
- Joe Puckett. The Apologetics of Joy: A Case for the Existence of God from C. S. Lewis’s Argument from Desire, p. 83)
Because a true atheist is a philosophical naturalist. On philosophical naturalism, transcendent, non-natural (super-natural) causes cannot exist.
Therefore, every event, to include a resurrection, has to have a purely physical cause.
It's like saying, snow cannot be non-white, since snow is white.
If one accepts as true the statement Snow is white, then it logically impossible for non-white snow to exist.
By analogy, if one accepts the statement All events have purely physical causes, then of course even a resurrection, should one occur, is not a miracle. Miracles cannot occur, since miracles are impossible. (That's called "begging the question.")
Pure philosophical naturalists are cognitively incapable of seeing or experiencing a miracle. Their only hope might be an experience of what seemed to them to be a Kuhnian anomaly, causing them to question the veridicality of their noetic framework (paradigm). As Kuhn has showed us, once a paradigm is locked into someone's mind, it is very hard to dislodge. (Paradigms are "obstinate.")
(As a theist, I reject the metaphysical statement All events have purely physical causes.)
My two books are:
Leading the Presence-Driven Church (Sept. 2017)