When disputing or discussing, it’s common to grant an opponent’s premise for the sake of argument. But we don’t always need to, and it’s not always desirable.
Take this example:
One who supports “Planned Parenthood” and the harvesting of infant body parts argues as follows:
“I thought that according to Christianity all babies go to heaven anyway. So why do you care?”
See what the person is doing? He’s not advocating for his own position, but seeking merely to reduce the Christian view to absurdity.