The Difference Between Miracle and Mystery

A miracle is something that occurs in the natural world that cannot be explained by natural means.

A mystery is something that exists that we cannot fully comprehend.

For example, someone being inexplicably healed of a disease is a miracle, because although our nature can grasp what has happened, we have no natural explanation for it. The Trinity, three Persons sharing one divine nature, is a mystery, because it is a concept that is beyond our reasoning to fully grasp.