What does your life mean and how do we know that is true?
First, we should understand that the answer to every question is in the King James Version Bible (KJV), the living word, inspired by God. Don’t use any modern Bible because many verses have been removed: see the list at the end*.
Now, let’s look at meaning.
Believing that Jesus Christ existed does not mean you are saved (many religions believe he existed). Attending a church without being born-again does not mean you are saved (look at the Sunday church-goers all around you). Having a born-again family member does not mean you are saved (salvation is not passed through family members). Thinking you are a Christian without being born-again does not mean you are saved. In all these instances, you are unsaved. (John 3:3, John 3:7, 1 Peter 1:23 KJV).
The life a person lives before being born-again is death (even if they thought they were a Christian). Why? (Romans 8:13 KJV). Because the physical mind is in enmity with God, which is hostility, hatred, and ill-will (Romans 8:7, KJV). It is not subject to the law of God; it is under the corrupt and evil influence of Satan and thus subject to the law of sin and death (Romans 8:2, KJV). More than 99% of the planet lives in this false state of reality, which is darkness and death. A pseudo-reality (1 John 1:5, Acts 26:18 KJV).
However, being born-again and living in Christ Jesus subjects us to the law of the Spirit of life, which makes us free from the law of sin and death (John 3:5, Romans 8:2-3 KJV). This is God the Father’s state of reality: truth. Very few humans live in light and life (John 8:12, Ephesians 5:8 KJV).
Now we see why only if we are born-again can the Spirit of God (the Holy Spirit) dwell in us, giving us life and not death (1 Corinthians 2:14 KJV).