OK fair enough I suppose you’ll advise me not to bother engaging liberals as you’ve probably been there and done it and found it’s a waste of time ?
In the face of overwhelming, factual evidence however there's a chance to sway anyone with a minimally open mind. Some liberals can be swayed that way (I've had that success) others cannot.
For example, I can present overwhelming evidence proving my prior point about the ACLU to 10 liberals. Some of them may see the overwhelming evidence and open their eyes. Others will claim the evidence was from "Faux News" and therefore couldn't possibly be right, and that "Faux News" should be taken off-air.