And he who ascribes partners unto Allah, it is as if he had fallen from the sky and the birds had snatched him or the wind had blown him to a far-off place.

Allah, subhaanahu wa ta'alla, compares Tawheed to the skies. And He compares Shirk (associating partners with allah) to falling out of the skies- which are vast and wide-to the lowest of the earths. And he compares ones desires that lead him to Shirk to the wind; wherever the wind blows/whatever his desire is, he will follow it; like a feather in the wind. Wherever the wind blows it, it (the feather) will go. And he compares the shayaten (devils) to to the birds, that is, every single Shaytaan (devil) will get a bit of the meat...every Shaytaan is happy with this man. The punishment is also mentioned here. That is, the person is falling down to his death... the wind blowing him to a far away place and the birds coming in and eating him..a terrible death

Taken from: "A critical analysis of Shirk" Lecture, by Yaasir Qahdi, with slight moidification.