I doubt you'd be comfortable with an open Satanist preaching his views in the public square. Or, how about a fundamentalist Muslim? That might bother most Christians more, ironically enough.
Sorry, I'm not trying to bait you. I'm all for free speech, but there are forms of street preaching, however, that amount to verbal abuse or harassment.
People shouldn't have to endure being called sinners for walking down the street. I don't care if it's a 15 year old in miniskirt, a gay couple, or whatever.
Giving them a piece of your mind right back doesn't help, it just reinforces their perception of themselves as misunderstood martyrs in a degraded society.
How does that kind of preaching not violate the admonition not to judge others lest ye be judged, or to let the innocent cast the first stone, or not to look to the speck in another's eye but the log in your own? I'd include the admonition to love thy neighbor, but these kinds of preachers tend to insist their message is 'love' as it brings the hope of salvation. I doubt the people they attack feel very loved by God while the crazed preacher is screaming at them.