I'm not very active anymore in commenting on dawah sites and refuting christians. However, I do on occasion pop by your site and I'm quite impressed by how you handle the likes of Sam and other haters. You seem to have a solid faith and I hope you keep up the good work.
Anyways, I've always thought about what makes people like Sam tic and this article, http://www.independent.co.uk/life-style/gadgets-and-tech/news/online-trolls-are-psychopaths-and-sadists-psychologists-claim-9134396.html might explain the behaviour of some of the frequent commentators on your blog.
I know that the thought has on occasion already struck your mind, but I thought that it might be an interesting read.