Hebrews 9:27,28 "Just as man is appointed to die once and then to face judgement, so was Christ sacrificed once to take away the sins of many, and He will appear a second time, not to bear sin, but to bring salvation to those awaiting Him."
Notice He will bring salvation- it's not permanent until we have been found faithful till the very end.
Jesus died one time for all people- for all in the past who obeyed God (144,000), and all who would obey God in the future (the promise is for you, your children, and all who are far off (future christians not born yet), as many as the Lord will call).