What Should I Say to a Reformed Christian Who Dismisses Many Non-Believers as Lost Causes?

Questions about the best way to respond to someone who believes in double predestination and who dismisses many non-believers as lost causes and whether someone who believes they need faith plus works for salvation can still be saved by their faith.

• What’s the best way to respond to someone in the double predestination camp who vocally dismisses many non-believers as lost causes?
• Can someone who believes they need faith plus works for salvation still be saved by their faith?