Seriously, I have never understood this particular aspect of theology: how does someone's death liberate you---2000 years later---from sin? "How," means the mechanism or process by which this occurs.
Try mere Christianity by CS Lewis
But just as the sin of one man condemned the entire human race (if I am wrong show me someone who is without sin) the atoning act of one Man who is also God saved the entire human race.
The exact mechanics of how this works? - I may or may not know when I reach Heaven. The important thing is not how it works but that it does.
Freepmail me and I’ll walk you through it. For a reasonable children’s allegory watch The Lion, The Witch, and The Wardrobe.
I was trying to determine how sincere you were with your question in my previous response. I can tell that you are sincere by your responses to mine and others.
My opinion is that others have answered this better than I could (I’ve even learned some things from them). I would read the Bible for a better understanding, but I caution people when they’re reading it, to keep in mind who it was written to, the context of the times, and the possibility that since you aren’t a practicing Jew of those times, you may not understand all of the Old Testament, or a “Galatian” or “Corinthian”, etc., you may not fully understand all of the New Testament.
I would also suggest reading “History of the Jewish Wars” by Josephus for a look at Preterism, and www.tentmaker.org for studying the possibility of universal atonement (related to the concept of Jubilee in the Old Testament). Both of those ideas have helped me a lot. Your mileage may vary. Good luck to you!