A person you work with - Colleague
Someone you know a little - Acquaintance
Someone in love with themself - Narcissist
One who does not believe in the existence of God - Atheist
One who is unsure about God's existence - Agnostic
One who sneers at the beliefs of others - Cynic
A person skilled in many different areas - Polymath
A prejudiced person against religion - Bigot.