Just consider our situation
We are each spiritual beings temporarily operating a physical body. It is like considering a driver of a car. The driver gets inside the car and drives it, and the car becomes an extension of the driver. The driver also begins to identify with the car.
Now just consider if a car drove out onto the freeway and began swerving between lanes and crashing into other cars. What would happen? Other cars would careen off the freeway, likely totaling their car and injuring the driver. Quite a bad situation.
But what would happen to the swerving driver? They would also likely spin off the freeway, wrecking the car and injuring the driver. Why? Because when one car hits the other, both cars will careen off the contact. And with freeway speeds as they are, the careening will leave both drivers out of control of their spinning cars.
This type of incident creates a basic principle of the freeway for most drivers: An accident on the freeway can be dangerous to both drivers due to the rates of speed the cars are driving at.
And as a result, most of us are extra careful when we drive on the freeway. Most people have seen the gory accidents on the side of the road. Most people have seen the statistics. Thus most people are careful. Why? Because they know that they will be just as prone to be injured as the other guy. In other words, there are consequences to hitting someone.
This same principle applies to living within a temporary physical body in the physical world, but many of us do not realize this, because the reaction time is sometimes delayed.
This world is programmed with consequences
The basic principle of the physical world is one of consequences. When we hurt someone else's body, our body will receive a similar pain at that time or some time in the future. When we mistreat someone's body, our body will be mistreated at some time in the future. When we steal from someone, our freedom gets taken from us as our body gets tossed in jail or suffers other consequences.
The consequences go on and on. None of us are aloof to suffering the consequences of the physical world - either within this physical body or in a future one.
As long as we are acting with self-interest, there is a consequence to every action in the physical world.
Why is the physical world a place of consequence? Because this is how the Supreme Being set it up. But why?
Because the Supreme Being wants us to return to the spiritual world - our home. And this is the consciousness of the spiritual realm:
"Do to others as you would have them do to you."
Note that Jesus is not saying "Do to others so they will do the same to you." Jesus is not talking tit-for-tat here. He is not talking business. He is not talking about a business relationship where if I do something good for you, you will return the good deed.
What Jesus is referring to is caring for others. Treating others the way we would want to be treated - regardless of how we are being treated or will be treated.
Real caring for others is not a business relationship. It requires considering others as more important than ourselves. This is the consciousness of the spiritual realm.
This is our original consciousness. Each of us by nature is loving and caring. We need to love and care by nature. The Supreme Being created each of us to exchange a relationship of love and caring with Him and others. This is why even the most wealthy and famous people derive more satisfaction from caring for others. This is our true nature.
The true state of this consciousness can only come when we have re-established our relationship with the Supreme Being. This is a relationship of love and caring. It is a relationship where we come to understand that the Supreme Being loves us unconditionally and cares for us without condition.
Most people want love and care from other people because we are feeling empty. We are feeling empty because we are not seeing the love and care the Supreme Being has for us.
A person who recognizes that love and care from the Supreme Being becomes fulfilled. They no longer need the love and care of others because they have the Supreme love and care from the Supreme Being. They no longer strive for the attention of others, or the admiration or respect from others. They know that the Supreme Being provides them with all the love and care they could ever need.
Thus, realizing this love and care from the Supreme Being means we don't have to seek it from others. We can then care for others without needing them to care for us.
Only then can we truly follow this principle laid down by Jesus. This is why Jesus said just a few sentences after this statement:
"Be merciful, just as your Father is merciful." (Luke 6:36)