Antithesis

Antithesis is a figure of speech that juxtaposes two contrasting or opposing ideas, usually
within parallel grammatical structures. Antithesis works best when it is used in conjunction with parallelism, since the repetition of structure makes the contrast of the content of the phrases as clear as possible. The word “antithesis” has another meaning, which is to describe something as being the opposite of another thing. The word antithesis has its origins in the Greek word antithenai, meaning “to oppose.” The plural of antithesis is antitheses.
 

Antithesis is basically a complex form of juxtaposition. So its effects are fairly similar –
by contrasting one thing against its opposite, a writer or speaker can emphasize the key attributes of whatever they’re talking about. Antithesis can also be used to express curious contradictions or paradoxes.
 

Example
To err is human; to forgive, divine. (Alexander Pope)
This example is used to point out that humans possess both worldly and godly qualities; they can all make mistakes, but they also have the power to free others from blame.