“Jesus replied, 'You must love the Lord your God with all your heart, all your soul, and all your mind'. This is the first and greatest commandment. A second is equally important: 'Love your neighbor as yourself'. All the other commandments and all the demands of the prophets are based on these two commandments.” Mat. 22:37-40, NLT
...all other commands are based on these...
“Hurt not others in ways that you yourself would find hurtful”. Buddhism
“If you want others to be happy, practice compassion. If you want to be happy, practice compassion.” Dalai Lama
“Do not do unto others what would cause pain”. Hinduism
“Not one of you truly believes until you wish for others what you wish for yourself”. Islam
“I am a stranger to no one; and no one is a stranger to me. Indeed I am a friend to all”. Sikhism
“Blessed is he who preferreth his brother before himself.” Baha'i
“Never impose on others what you would not choose for yourself.” Confucianism
“What you wish your neighbours to be to you, such be also to them.” Greek Philosophy
“I ask you a question - “Is sorrow or pain desirable to you?” If you say “yes it is”, it would be a lie. If you say, “No, it is not” you will be expressing the truth. Just as sorrow or pain is not desirable to you, so it is to all which breath, exist, live or have any essence of life. To you and all, it is undesirable, and painful, and repugnant.” Jainism
“In everything you do, do unto others as you would have them do unto you”. Christianity
“What is hateful to you do not do unto your neighbour that is the entire law; all the rest is commentary”. Judaism
I know a tactic is the claim that the Golden Rule isn't a single rule, but a pair of them – the first – 'You must love the Lord your God with all your heart, all your soul, and all your mind'– being the first and missing part, thus discrediting those stating only the second: 'Love your neighbor as yourself'. However, I don't believe this.
If we are 'right' with God (the first Golden Rule) then we will naturally become 'right' with our fellow-creatures and neighbours (the second Golden Rule). It stands to reason that this is also true in reverse. If we are not perfectly 'right' with our fellow-creatures and neighbours, then we are also not 'right' with God.
Can any of us honestly claim we are perfectly right with our neighbours? Can any of us honestly claim we are perfectly right with God? It becomes a moot argument. These two conditions are tied together. They are indivisible. One is the byproduct of the other.
It strikes me that these are all variations of The Golden Rule; or in fact, they actually are the Golden Rule. But why are they discredited when spoken from a differing source, or from a different culture?