"My answer is, that this sort of argument is common to all those who write against Luther. They assert the very things they assail, or they set up a man of straw whom they may attack".

— Martin Luther

A straw man argument involves misrepresenting your opponent's argument and then attacking that misrepresentation instead of their actual argument.

Example:

Person A: "I think the best explanation is that God is identical to the universe because only this view of God can be justified."

Person B: "You're just redefining the term God."

In this example, Person B misrepresents Person A's argument by distorting it to make it easier to attack. God is a being, the supreme being. Person A is actually saying that the universe is a being not that God is a blob of all the matter there is. Person B creates a "straw man" by distorting the original argument into something more extreme or different, then argues against that distorted version rather than the actual point made by Person A.