And I will always be glad I learned these teachings early on, and eventually learned their truth from trying to do the exact opposite and suffering the consequences.
I believe this children's hymn, whose lyrics anyone in any Christian faith could agree with, along with anyone ecumenical, truly embodies the spirit of Christmas, even though it isn't a Christmas carol:
Love One Another
As I have loved you, love one another
This new commandment, love one another
By this shall men know, ye are my disciples,
If you have love one to another.