You should be a spiritual mustard seed, not a mentos geyser

According to C.  your spirituality (and how you act) should be like the return we get from that planted mustard seed.  Not necessarily showy, but a steady yield.  It shouldn’t be like a mentos geyser.  Flashy, lots of fun for the moment, and over quickly. 
I wouldn’t have thought you could pull an object lesson out [...]