He WILL outgrow this eventually, but until then, you need to keep all shoes away from him.

It is boredom - he needs something to do, so get a bunch of cheap chew toys to give him.

the above is true... we tried several different things in our house... 1) put a few pennies or some old un-needed screws in an old (washed out first) soda can & close the hole w/ duct tape; when the pup does something you don't like shake the can at them & the noise will startle them. 2) we have an old worn out unwearable belt, it is split in 2, & the first time we used it we held both ends of the belt a little slack & snapped it taut ... it makes a loud crack & startles them... 3) when caught in the act of actually eating one of my daughter's shoes I grabbed the shoe from his mouth & yelled at him while shaking the shoe in his face. I said, "is this YOURS? are you ALLOWED to eat shoes?" & bopped him on the nose.. (didn't hit him hard, just startled him) he no longer eats shoes
We used to keep him crated when we were either asleep or away & one day he didn't want to go into his "house" & we actually reasoned with him... told him that if he could be a good boy & not destroy anything that we would let him sleep on the couch (his favorite spot) & he's been good ever since...
dogs really are smart & DO understand us
Good luck