What is the common understanding of all enlightened people?

There are many sutras and they are on different topics. Many people got enlightened by asking different sutras. Ven. Saripuththa thero got sothapanna by asking to cause and effect. Ven. Kondanna thero got sothapanna by asking to middle path and kamma. So, What is the core teaching of **all** the suttas ? What wisdom all they have in common ? **Edit:** I think all people have some understanding of the world. Lord Buddha recognized those and help them to complete their understandigs. Ex: When Ven. Sariputhta thero hearing to the Cause and effect, He already have the understanding of Impermanance. (Because of that, He started to find the truth).