Now there was a man in Jerusalem, whose name was Simeon, and this man was righteous and devout, waiting for the consolation of Israel, and the Holy Spirit was upon him.
And it had been revealed to him by the Holy Spirit that he would not see death before he had seen the Lord's Christ.
And he came in the Spirit into the temple, and when the parents brought in the child Jesus, to do for him according to the custom of the Law,
he took him up in his arms and blessed God and said,
"Lord, now you are letting your servant
depart in peace,
according to your word;
for my eyes have seen your salvation
that you have prepared in the presence
of all people,
a light for revelation to the Gentiles,
and for glory to your people Israel." (ESV)
From Genesis to Revelation, the Bible is about a rescue, God's rescuing people from His own wrath that they would bring upon themselves because of their rebellion against Him. As early as Genesis 3:15, we have recorded what is known by Christian theologians as the protoevangelion (the first gospel). Throughout the Bible, there is a scarlet thread of redemption.
Overall, the Bible is not to be read as a "how to" book on the subjects of living (e.g. how to have a good marriage, how to raise children, how to select the right profession, etc.). The Bible does address those issues (for the Christian), but that is not the theme that God has in it for us. God's main concern for mankind is that each one of us would be redeemed to Him by trusting in the saving work of His Son, the Lord Jesus Christ.
Just as the main theme of the Bible is God's redemptive plan, the main theme of the Christian's life should be the Gospel of our Lord and Savior Jesus Christ.