“This is the sum of duty: do naught unto others which would cause you pain if done to you.” –Brahmanism, Mahabharata 5: 1517

“Hurt not others in ways that you yourself would find hurtful.” –Buddhism, Udana-Varga 5:18

“Thou shalt Love thy neighbor as thyself.” –Judaism, Leviticus 19:18

“Whatever is disagreeable to yourself, do not do unto others.” 

–Zoroastrianism, Shast-na-shayast 13:29

“One should always treat others as they themselves wish to be treated.” –Hinduism, Hitopadesa 

“Surely it is the maxim of loving kindness: Do not do unto others what you would not have them do unto you.” –Confucianism, Analects 15:23 

“Regard your neighbor’s gain as your own gain and your neighbor’s loss as your own loss.” –Taoism, T’ai Shang Kan Ying P’ien  

“That nature alone is good which refrains from doing unto another whatsoever is not good for itself.” –Zoroastrainism, Dadistan-I-dinik 94:5

“No one of you is a believer until he desires for his brother that which he desires for himself.” –Islam, Sunnah 

“What is hateful to you, do not to your fellowman. That is the entire law; all the rest is commentary.” –Judaism, Talmud, Shabbat 31a

The golden rule is found in every major religion. It is the main theme of all of them, and it sums up all the lengthy spiritual texts from all over the globe in one sentence. It is really simply saying to love each other. 

Enlightenment is seeing the One in all things, acknowledging that it is the same as your true identity, and acting accordingly. Acting accordingly is treating others how you would like to be treated because you recognize that they are you. It is that simple.

From the heart space, we automatically do this. But we forget, hence the rule, the great reminder that we are One thus act like it and treat others as not separate from you.