It isn't actually racist in that latter case, but a valid point otherwise.
I regret the atrocities that people committed in the past, but I myself did not commit any of those atrocities. It's true that, descended from European immigrants as I am, I probably benefited indirectly from those things, but the fact of the matter is that I could not have done a single thing to stop them. The most I can hope to do is try to keep such things from happening again.
However. When Christians disregard those horrible events that happened because of Christians who came before them, when they try to pretend that they weren't done by real Christians, when they rewrite history by whitewashing the reputations of previous Christians, then they are committing an atrocity of their own. They're perpetuating the myth of infallibility and creating the conditions for future Christians to repeat those crimes and atrocities of the past.
A modern-day Christian may not bear guilt for the Inquisition or the Holocaust, but they have the responsibility to work to ensure that such things never happen again, or else they're setting the stage for future religious atrocities.