Before you had to be pious and follow God's Law to the letter and be a leader amongst your people to get to Heaven. You could be the embodiment of righteousness and piousness and still not enter the Kingdom. With Jesus dying for us< spending his three days in hell and rising again to teach, then further ascension into Heaven allows for all of God's children to enter into Heaven. All you must do is repent for your sins, instead of attone for them.