How It All Goes Down
In the beginning, God did a whole bunch of stuff. That's the short version, at least.
Basically, God created the world and then made an agreement with the people living in it: if they put their faith in him, he would be their God. It was a pretty sweet deal, but things weren't working out so well. The people didn't always trust in God…and God wasn't super psyched about that.
Enter the New Testament. According to this collection of books, when God saw that his old covenant with the people was no good, he sent his one and only Son to Earth...where he was promptly put to death. On a cross. It was all part of God's plan, though: turns out that Jesus' death actually saved the world.
Quick rewind: back in the day, people could make up for their sins and get right with God by offering animal sacrifices in the tabernacle. A high priest would go into the super special inner sanctuary of the tent and sprinkle animal blood on the Ark of the Covenant. (Yeah, the cleanup was a real pain.) But according to the New Testament, when Jesus came to Earth, he acted in the role of the high priest. He went into God's sanctuary (i.e., Heaven) to put in a good word for humanity. This time, he didn't bring any animal blood with him—he used his own blood because crucifixion is pretty darn gory.
God was so thrilled that he totally forgave everyone's sins and decided to start over fresh. Now, says Hebrews, because of Jesus, human beings are living under a "new covenant" with God. Of course, that doesn't mean people are off the hook. Folks still need to put their faith in Jesus in order to get in good with God. That means keeping the faith even if it means being shunned, thrown in jail, or even killed.
Hardcore.