The Golden Rule. Some call it the Silver rule: Do not do unto others what you wouldn't want done unto you.
Also called the principle of reciprocity - and is present in not just human cultures around the world, but in animals as well.
Well almost James.
You see Jesus Christ added onto this rule - to do good to those who hate you and revile you. While other religions state it in only in a ‘negative’ context, Christ reversed it as also as a ‘positive.’ If a soldier bids a christian to carry his pack a mile Christ stated we are to carry it 2 miles.
Most religions have in mind to try to ‘earn’ their way to heaven through good deeds. Now the Muslim religion is more than just religion as it seeks to dominate or decimate all others and is a satanic-inspired system.
But Christ preached love and belief in His perfect sacrifice as our only option for salvation. Christians and Jews who are/will be in heaven some day are not there on the own self-righteousness rather the imputed (to believers) righteousness of Christ. See Abram in Genesis.