The sentence that describes Eliezer's viewpoint of the fact that the mud hides his shoes is the last one: "Eliezer views the mud as an act of God out of habit because that is how he viewed the world before entering Auschwitz."
Since his arrival in Auschwitz, he has lost faith in God. This is an example of verbal irony. Other prisoners are stealing shoes because they need them but since Eliezer's are covered in mud, the other ones don't notice they are new and he gets to keep them.