Is a Humanist an Atheist?

The answer is not necessarily.

A  humanist approaches the world in a secular way. Problem solving etc are done without the aid of supernaturalism (and that means without the aid of gods). There are lots of people who believe in supernatural things but chose to approach life secularly anyway. These people would be pragmatically a-theist, but not theistically a-theist.

However, Humanism, as a term, was coined to describe a specifically non-theistic, non-religious approach to living well and ethically. Our morality is unapologetically grounded in human compassion and we don't appeal to gods or supernaturalism at all in our moral reasoning.  Lots of people of faith agree with this approach to morality and problem solving and find that it blends well with their theism. For instance, people who have taken my Living Made SImpler course and read my books tell me that it provides additional grounding for the theistic morality they hold. But because the word Humanism is a specifically secular approach and because there is no other term to describe such an ethical approach, people of faith who share this value system describe themselves as being humanistic as opposed to humanist.  Meaning, they agree with humanism, but are still religious or theistic in some way. 

As a result there are groups for Humanistic Judaism, Humanistic Christianity, Humanistic Islam and humanistic whatever.  A Humanist is someone who is secular and therefore not religious.  Someone who is humanistic - approaches whatever their theistic beliefs are in a humanistic way.  

To learn more about Humanism consider getting my book: The Handy Humanism Handbook
or check out this online course: Living Made Simpler