The point of debating (or verbal fisticuffs, school-yard style, which is what it really is) them is winning the audience over to your side if at all possble.

Ideally, the audence will go "Oh, what a nice and intelligent man/woman. He/she speaks my thoughts and feelings what I haven't been able/dared to voice. How wonderful to know I'm not alone in thinking/feeling this way, and sham on that so-and-so opponent of his/hers for behaving the way it does!"

That way, the audience will be full of potential for further opposition to the left (not a term I tend to use since it's rather meaningless and in error, but it's the local vernacular on this Stack).

Of course, should you actually meet someone who is genuinely interested in an issue (say, transsexualism) and approaches it with a "What is this?"-mindset rather than ideological dogmatism, a real debate where both sides start with pooling their perspectives and knowledge is possible, but such opportunities are increasingly rare in my experience; there's simply too much selection pressure on people for them to opt for real debate instead of replaying the opening scenes of the two troops of apes in a 'A Space Odyssey'.