I've never cared for that answer, but it might speak to those who actually would ask that question.

My answer would be "because I'm a nice human and people don't do that to each other, unless some dogma teaches them that to do so is fine by their creator. The "Do unto others as you would have done to you.' is not owned by Christianity, as there are versions of that all over humanity, and seems to be seldom practiced by the most religious zealots. I am human and practice being a caring human as much as humanly possible. It has nothing to do with religion."