I expect you’ve heard of CS Lewis. His conversion story is representative. One day he rode to the zoo in a motorcycle sidecar. Later he said, “When I got into the sidecar I did not believe that Jesus Christ was God’s Son, and when I got out I did.”
I read your conversation with null and void with fascination. The two scriptures that come to mind are:
1) John 6:44 No one can come to Me unless the Father who sent Me draws him; and I will raise him up at the last day.
2) Ephesians 2:8 For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, 9 not of works, lest anyone should boast.
The conclusion: God must act before we can be saved. He acts by giving us the faith to believe. Then we must act on that faith He gives us.
Thus, no one will be saved without God’s action, so no one can boast.