The truth is that atheism is an idea that just didn't (and doesn't) work. It flies in the face of everything we implicitly and explicitly know about ourselves and the cosmos. It's just too unbelievable to believe. I know that statement cause my atheist friends to lapse into apoplectic gasps, since it's the line they love to lay at the doorstep of the believer, but that's just the way it is.
McGrath includes a telling quote from John Updike:
"Among the repulsions of atheism for me has been its drastic uninterestingness as an intellectual position."
This is at least partially the case because athiesm is not so much of a position, but a counter-position - having its only real grasp to relevance as a derivation of the thing it abhors.
I've often pondered how curious it is that atheists, who really shouldn't care one way or the other what other people believe (unlike religionists - who, by the basic definitions of most faiths, have a command to care what others believe) are most frequently the most ardent, outspoken, obnoxious and fundamentalist evangelists for their faith. See this quote from Howard Thompson, editor of Texas Atheist:
Total victory is the only acceptable goal in a mind-control war because humanity is diminished so long as a single mind remains trapped in superstition by programming or choice.
Obviously, atheism will be around as long as humanity exists in its current form - not because of evidence, philosophy or reason, but because of moral choice (or the desire to avoid such things).