Because I'm not going to be kind to a bunch of lying, hedonistic, degenerates, who spend their days blaspheming God, living in sin, and spreading blatant, a-historical lies about the Bible and the Church.  

A large % of the population has been conditioned/brainwashed to believe that anything which sounds "harsh" or "insensitive" is hateful.  The word 'hate' is misused in our day and age.

It matters not where you go or what you do or what you believe (in), people will be unkind.
I really have no idea as to the unkindness you seem to have suffered, but ultimately (and this is my point) it is up to you as to how to respond to said unkindness. Aren’t we informed to turn the other cheek? It can negatively affect you inside, in your heart, but only if you allow it.
Oftentimes unkindness is mistaken for actual, true and genuine kindness. All too frequently someone will point out or (GASP) correct our mistakes or errors and it will seem negative. But if we actually take the time to understand our faith, and view absolutely everything through that prism, we COULD see that the perceived unkindness is in fact a kindness: that is, that it is something that keeps us on that narrow path to loving knowing and serving God. And getting into heaven (which I lovingly call the party in the sky, or getting to hang out with God)