If it's okay, I'd like to give my two cents here.
I think it's important to keep in mind something that Bishop Fulton Sheen once said: "Win an argument, lose a convert." I recognize the potential that the internet has as an evangelical tool, considering that is all the internet really is- a tool. Nevertheless, I have (over time and through a school of hard knocks in which my arrogance and retaliatory personal attacks and other inexcusable behavior has probably served little but to lead others even farther away) learned that most attempts at apologetics are little more than petty arguments and do more damage than good.
Yes, it is indeed possible to be GOOD at arguing, and St. Peter instructed us to "Always be ready to give an explanation to anyone who asks you for a reason for your hope..." (1 Peter 3:15) but I think that one should be aware of his or her strengths and weaknesses. Not every Christian will be good at "debate;" far from it.
Another thing to keep in mind is that even if we assume that we are good at debates and can keep everything civil and never once raise our internet voice as if we were Christ Himself typing away, is that mere arguments never convert anyone. I don't need to provide "evidence" that such is the case. Everyone that actually thinks about it knows that right away. And so we remember the words of St. Francis of Assisi: “Preach the Gospel at all times, and when necessary, use words." It should not be considered our job to "convince" people; it is our sacred duty to INFORM them- when the are wrong, when they sin, etc, and even more importantly, to love them and care for them as our brothers and sisters and perform the works of mercy, etc. The job of convincing others is the job of the Holy Spirit Himself, and the duty of each individual to decide for themselves.
So, if one were to heed my advice on this topic, say what you have to say and back out; do not drag things on and engage in an intellectual back-and-forth unless you know good and well you have a gift for such a hefty task, and sometimes not even then. So now it's probably time for me to heed my own advice, no?