Of course, you may be thinking, why does Jesus get to declare his sins null and void? What about the victims who actually suffered? Jesus is effectively saying, it doesn't matter what the victims think or how you hurt them. As long as you believe in me, here's your "Get Out of Hell Free" card. Besides, it doesn't appear that Holmes is in possession of all his marbles, so there is a good chance that he is not even entirely aware of all that he did. According to Christian doctrine, he can repent for this and then go do it again, and again, and again. As long as he finally repents on his death bed and accepts Jesus then all will be forgiven and he will get to enjoy the same eternal bliss as the most innocent and peaceful people who ever lived.
Can you imagine that conversation in Heaven.
Holmes: "Hi, Saint Peter". Sorry abuot that killing a bunch of people thingy, but Jesus said it was all good because I believe that He turned some water into wine a couple thousand years ago and then walked on it. "
Peter: "Very good, Mr. Holmes, we will put you in the suite right next to Mother Teresa. By the way, what kinds of fantasies would you like to experience in heaven?"
Holmes: "Well, I was wondering if you could dress me up like the Joker, and let me kill people again."
Peter:" Naughty, naughty, Mr. Holmes. Anyway, it's heaven so people can't die anymore. But we could let you pretend to kill people. Here's a video game console."