”And so upon you will come all the righteous blood that has been shed on earth, from the blood of righteous Abel to the blood of Zechariah son of Berekiah, whom you murdered between the temple and the altar.“ – Matthew 23:35 NIV

Interesting that he said that they killed Abel. Abel was definitely someone that was before their time and yet he said they killed him. This was when they had yet to even have the name of Jew. It has to do with an attitude of hatred and rebellion on their heart from God. Focus on doing right by God and others and you won’t be like Cain.