Many freethinkers engage in active online debates, on the Usenet or Bulletin Boards or elswhere, and in that process encounter Christians who get excessively defensive and hurt. Many freethinkers do not want to hurt people, and wonder how any progress can be made with such people, or if one should even try. I've been hashing it out in debates online since 300 baud modems, when there was no such thing as e-mail or a world wide web, just local BBS's, and I continued through the rise of Prodigy and The People Network, then to AOL when that appeared, and the usenet, and so on. Now I see it all as feedback editor of the Secular Web. The one thing I can tell you from all my experience is that you have to make a separate judgement call based on your total, personal experience, with each person online.
Some people are insane.
These people are not to be reasoned with. No one among their friends or family, not even their priest, will think of them as insane, just devoted. You must not converse with such people. They won't take the advice, but this is your way of washing your hands of the problem. If they keep pressing, keep sending the exact same mail.