In fact you only feel ,murder,rape etc are wrong because the random chemical reactions in your brain make you feel that way. Not because it truly is right or wrong. I may be like hitler and think murdering is good, what makes your random chemical reactions correct and mine wrong?.
Why do you say that the chemical reactions are random? Anyway, there are some electrical ones as well.

I may be like hitler and think murdering is good
He didn't believe murder as a principle or in general was a good. He believed in eliminating threats and furthering the prosperity and security of his Volk. His ideas didn't hit the mark...

what makes your random chemical reactions correct and mine wrong?.
We could ask the same of you. That leaves us at an impasse. The first to kill the other wins, I suppose.