Pertaining to the question of meaning and purpose in life:
If you believe that there is no God then you must conclude that
a. You come from nowhere.
b. You come from no one.
c. When you die you are going nowhere.
d. When you die you are going to no one.
e. You have no objective reason to live.
According to the atheist, your whole existence is just matter in motion. Your thoughts, emotions, and actions are just chemical reactions determined by a set of naturalistic factors. The whole universe came about by chance. You were not intended and your entire being, all that you are, is a complete and total accident. Inevitably, the result is the same for all. We will all one day die and cease to exist. According to the atheist.

The Christian, however, believes he/she was created by a single preeminent and divine being. This being who knows everything and who has designed all things, exists eternally in perfect, loving relationship as Father, Son, and Holy Spirit. He is the Triune Creator God. This being deeply loves his creatures and created human beings in order to share His wonderful, perfect life with them so that they could glorify Him in doing so. This is the Christian's purpose in life. The Christian has real, objective meaning for existence because God has reached out to all humanity in Jesus Christ, God incarnate, who bore the sins of the world and gave himself as a living sacrifice so that through faith in Jesus Christ humans could be saved from their sins and their selfish, Godless way of life and begin to be transformed by the Holy Spirit to the image and likeness of Christ, all for the glory of God.

The Christian believes this is why human beings were created and what human beings were intended for: right and loving relationship with God and others so that God could be glorified in them.
In essence, the Christian knows that:
a. They come from God.
b. God is perfect love.
c. God therefore loves them deeply and wants to bring them into his perfect life.
d. They exist to bring glory to God because from before time began, that's what God had purposed for them to do.
e. Bringing glory to God is the most fulfilling purpose for their life.
f. One day they will live in perfect relationship with Him and all of God's children in Heaven forever.

Without God there is no objective meaning or purpose for human existence.

The atheist believes he lives for no reason and no one.
More importantly, the Atheist lies to himself and says that he comes from no one and that no one loves him. Remember, emotions, intellect, actions, thoughts, whatever it is, it's all just chemicals fizzing for no clear or objective reason (according to the atheist). Therefore there is no such thing as love.

The Atheist fails to see that love is real and that it was love that brought him into existence.

"He who does not love does not know God, for God is love." 1 John 4:8