Did it ever occur to you that her argument would be just as valid if you reversed it? In other words, isn't it just as logical to say that some people don't believe in God because they want to be alone in the universe? Then they'd be free to live any way they wanted to, with no moral restraints. Think about it carefully - because it's true.
How do I know God is real? One reason is because of the wonders we see around us. From the most distant galaxies to the smallest subatomic particles, the universe exhibits amazing order and complexity. It's far more logical to conclude that God created it all than to claim it happened by chance. Many centuries before telescopes and microscopes were invented, the Psalmist exclaimed, "The heavens declare the glory of God; the skies proclaim the work of his hands" (Psalm 19:1).
But I know God is real for an even greater reason: Over 20 centuries ago, God came down from heaven and walked among us. God became a man! Do you want to know what God is like? Look at Jesus Christ, who showed God's love for us by dying for us. He then proved He was divine by rising from the dead.
I invite you to look at Jesus Christ for yourself, as He is found in the pages of the New Testament. Not only will you conclude that God exists, but that Christ can change your life.