“Judge not, and ye shall not be judged: condemn not, and ye shall not be condemned: forgive, and ye shall be forgiven: / Give, and it shall be given unto you; good measure, pressed down, and shaken together, and running over, shall men give into your bosom. For with the same measure that ye mete withal it shall be measured to you again.”
In these words from Matthew 7:1 are encapsulated the message of nearly everything that I believe...what you do to others you are doing to yourself... when you judge people you will be judged in that same way.
It's hard to breakout of the idea that we are separate and that we can act towards others and not be affected by it. Learning to acknowledge the oneness of all is tough, especially in the modern world in which people may appear to self-serving and grasping - and different from us. It's an illusion. We are all part of the same thing.