The Bible.
It’s definitely not (Basic. Instructions. Before. Leaving. Earth.) That’s laughable and falls way short. Remember… “The Word became Flesh and dwelt amongst us.” The Word is the Creator in tangible form.
The Creator of all, engaged 40 ‘writers’ who did not know each other, who were spread out on 3 continents, over a 1500 year time span, all sharing details that validate each other’s message received. Even if some got added, or some got lost over the centuries…the person of Jesus and it’s main message did not. 
At its minimum The Bible is a library loaded with tragedy and triumph, hero’s and horrors of mankind that will capture your intrigue and capture better than a movie.
I have read it, studied it, prayed through it, and critical-eyed it. At its fullness, It is alive and relevant. Cutting. Life changing. The Scripture, in its completeness, is Jesus prompting you to rise and shine and live life to its full. It’s your wisest friend of hope, and your greatest rebuke of correction.
Have you just read it? Don’t just read it. Listen deeply to it. Slow down. Clothe yourself in it and with it. Take it in…Slow down in this short life! What’s your hurry? What are you working so hard towards? Where you going? How fast did your last 20 years go by? Your next 20 will go faster and then what?
Absorb The Word with the faith of a child…Daily, for the rest of your life. Don’t doctrinize it, systematize it, or theologize it like some foolish worldly education standard.
Become it.
Then you will fully be as you were created to be. It will be the greatest challenge of your entire life and you will celebrate its accomplishment in you for eternity with the others who did the same.
