Ironically, I would have agreed with that blog post when I was a Christian. I made essentially the same arguments. Yet, here I am now, evidence that it's poppycock.
The real problem with that line of "reasoning" is that they refuse to even remotely consider the possibility that they could be the ones who are wrong, that maybe, just maybe, Christianity really isn't true after all. They want everyone of every other belief system to consider the possibility that they're wrong, but they refuse to do it themselves. Been there, done that, and I've since then grown to realize that that attitude is the biggest stumbling-block there is to finding truth.