That being said, I always thought there always has to be a line (whether on-line or off-line) when dealing with this sort.
For instance, we have always known to keep away from missionaries, engaging them in conversation will not alter their pre-programmed mindset, it will only puncture holes in our own armor of Emunah.
Those that come in earnest, to seek, explore, find out, those we are bidden ??? ???? ???. To them there is a mitzvah of Tochacha. For them we must do whatever it takes to bring them back. Patiently, courteously, gently. Just like the four sons of the Hagadah. One who comes to scorn we chase him out. Others we deal with, each to their own method.
So when dealing with these issues here in the open, (even for those that come earnestly to seek) I think it would be prudent for some to take note and look elsewhere (all-important humor ones). For some, looking will only cause more doubt, disbelief.