If the digits of pi really are random (or at least patternless, see The digits of pi are not random.) then every finite sequence of digits must be in there somewhere (Or to put it a little more precisely, the probability that any given sequence isn't in the first N digits tends to 0 as N tends to infinity), so all you have to do is code up the above phrase into a string of digits by whatever means you like, then hunt through pi until you find it.
It's mildly entertaining to estimate how far you have to look: say we use a nice simple coding where we assign 2 digits to each character, so A=01, B=02, etc, and SPACE=27 (plus whatever other punctuation you like). Then for a phrase of n characters, we need a 2n string of digits. The chance that any digit in pi matches the one you want is 1/10, so the chance that your string occurs at a given point is 1/(10^2n). So you probably need to look at 10^2n digits of pi before you find your phrase.
So to find 'God is mathematics' you probably need to look at the first 10^36 digits of pi.
For 'To be or not to be', it's also 10^36. To find the complete works of Shakespeare it's unimaginably huge, but they will be in there somewhere (though the infinite number of monkeys might get there before pi does).
For 'Pi', it's just 10000 digits, so a place where it occurs has probably already been calculated.
Does any of this have any meaning? .1415
Okay if you care about mathematical accuracy please ignore the comments about probability in this node and read ariels nodes instead. I'm leaving them in because they show what I mean and this isn't meant to be a factual node anyway.