There are so many contradictions in the bible, if you really know your stuff, you can counter just about anything the religious manipulators throw at you. But this is one you can toss back almost any time they start messing with you.
"Therefore all things whatsoever you desire that men should do to you, do you even so to them. For this is the Law and the prophets."
-- New Testament, Matthew 7:12, from the Christian tradition, circa 30 AD
And if they don't speak that language...
"This is the sum of duty. Do not unto others that which would cause you pain if done to you."
-- Mahabharata 5:1517, from the Vedic tradition of India, circa 3000 BC
"What is hateful to you, do not to our fellow man. That is entire Law, all the rest is commentary."
-- Talmud, Shabbat 31a, from the Judaic tradition, circa 1300 BC
"That nature alone is good which refrains from doing unto another whatsoever is not good for itself."
-- Avesta, Dadistan-i-dinik 94:5, from the Zoroastrian tradition, circa 600 BC
"Hurt not others in ways that you find hurtful."
-- Tripitaka, Udanga-varga 5,18 , from the Buddhist tradition, circa 525 BC
"Surely it is the maxim of loving kindness, do not unto others that which you would not have done unto you."
-- Analects, Lun-yu XV,23, from the Confucian tradition, circa 500 BC
"One should treat all beings as he himself would be treated."
-- Agamas, Sutrakrtanga 1.10, 1-3, from the Jain tradition, circa 500 BC
"Regard your neighbor's gain as your gain and your neighbor's loss as your loss."
-- Tai-shang Kang-ying P'ien, from the Taoist tradition, circa 500 B.C.
"Do not do to others that which would anger you if others did it to you."
-- Socrates (the Greek philosopher), circa 470-399 BC
"Treat your inferiors as you would be treated by your superiors."
-- Epistle XLVII,11, from the Seneca tradition, circa 5-65 AD
"Be charitable to all beings, love is the representative of God."
-- Ko-ji-ki, Hachiman Kasuga of the Shinto tradition, circa 500 AD
"No one of you is a believer until he desires for his brother that which he desires for himself."
-- Koran, Sunnah, from the Islam tradition, circa 620 AD
"We obtain salvation by loving our fellow man and God."
-- Granth, Japji XXI, from the Sikh tradition, circa 1500 AD
Obviously a lot of people throughout history felt the need to get the pressure other people were putting on them redirected back at them.