I found this answer: What does "to take someone at face value" mean?
However, it didn't offer a word that conveys this meaning.
The word I'm looking for should fit in a sentence,
When Bob asserted that zombies are a real threat, she took his word [at face value] by virtue of his credentials alone.
Best Answer
The word you might need is "unquestioningly". http://www.merriam-webster.com/dictionary/unquestioningly