This is a somewhat confusing thing to achieve, highlighting liquid templating code in a code block, and made even more confusing by the title. Take this example from this article about I wrote about mephisto:

#previous link
{% if article.previous? %}
  {{article | previous_article | link_to_article }}
{% else %}
  <a href="/">home</a>
{% endif %}

To actually display the liquid template code you have to get crazy with the curly brackets; the code in the markdown (in my case) file actually looks like:

#previous link
{{ “{% if article.previous? “}}%}
    {{ “{{article | previous_article | link_to_article  “}}}}
{{ “{% else “}}%}
  <a href="/">home</a>
{{ “{% endif “}}%}

Typing that above leads to a sweet infinity effect, but do yourself a favor and don't copy/paste that, just take it from this post on github, because to actually type that I had to use “. Of course a proper way to do would be to extend markdown/textile in pygments to support the liquid templating language, but that's for another day.