Can someone explain what antithesis is in simple terms?
It means the pronounced opposite of something or someone already usually already stated.
Here are one or two examples of antithesis.
Cliff Richard to many is the antithesis of what is the normal image of a pop/rock star. (The normal image is of a hard drinking, drug taking, fast living individual who often dies prematurely, not a single, committed Christian who has had a career spanning over 50 years)
Andrew (Beef) Johnston is the antithesis of what expect the modern professional golfer to look like. (Johnston is an overweight individual who enjoys a drink and having a good time, unlike the almost robotic super fit immaculately dressed golfers who inhabit the professional tour).
Marxism talks about a starting point (thesis) a reaction against it (antithesis) and an outcome (synthesis). Capitalism would be an existing thesis, a revolution would be the antithesis and communism would be the synthesis.