It's simple! Believe!
Ugh... That word Christians like to use...
Let me explain!
The Bible states that God is the true God and that Jesus is the Son of God, yet Jesus is also the one true God.
The Bible also says that Jesus was perfect and sinless, and that he was born of the virgin Mary, He was not cursed with sin as those who come from human lineage.
The cost of sin is death, animal blood was used to cover the sin of man, but it could not clean man of it. Only perfect, sinless, divine blood, could wash mankind of sin.
Thus Jesus died on a cross, shedding His Blood on that tree (the cross) washing away the sin of mankind. Furthermore, Jesus was raised from the dead, conquering death showing His power as God, sovereign over all things.
But, to be written in the Book of life, there is one thing you must do!