Firstly, that is a part of a whole set of instructions for a particular set of people, in a particular time. Secondly, it doesn't say you will land in hell for coveting your neighbours wife. Thirdly, it's not a superstition. jan.
You misunderstand the question. The question was not "name a superstition that is upheld by authority/scripture" (the "it" you refer to above); the question was "give an example of a theist superstition". There are lots of theists who do believe that committing sins such as adultery will land you in hell.
And I guess getting caught will land them in hot water, the dog house, or hell. I know lots atheists who believe that. I guess that's an example of atheist superstition. I don't believe there are lots of Christians who say that. I personally have never heard any. jan.
Of course! Atheists haven't cornered the market on rationality. I would as soon question a person (atheist or no) about his belief that walking under a ladder is bad luck. And, about that, he may or may not be rational - he may actually say "I know in my heart that it is true." The question wasn't 'how many'.