Christlike love and kindness. Yes, that was him. He always treated his viewers with respect, regardless of their age. He never talked down to us, never had a condescending attitude, never had to "dumb down" his message. He was able to talk to us on our level, and he instilled that childlike wonder and innocence in us, which is exactly what God wants. So without patronizing to any particular denomination or creed, he still did God's work in a way that could reach everybody.
There was a special that aired just a few months after I was born. Mr. Rogers talked to kids (though Daniel) about the aftermath of Bobby Kennedy's assassination. He explained that we live in a violent world, bad and scary things happen, and he helped kids overcome their fears, and try to help them understand why things like this happen. He didn't sugarcoat anything, but he was as loving, sensitive, and patient as he always was.
If you ever get to visit the Paley Center in New York (I believe there are also branches in L.A. and Chicago), they have this episode in their library. Worth its weight in gold.