“the god of this world has blinded the minds of the unbelieving so that they might not see the light of the gospel of the glory of Christ, who is the image of God.” – 2 Cor. 4:4
There are many instances of staunch atheists going on a quest to definitively disprove Christianity only to discover its truth; Augustine, C.S. Lewis, Lee Strobel, and many more.
Here is a contemporary case: