agree with you, that a person can not manufacture the faith to believe that God exists. But once he has that understanding by faith, (Heb 11) it is in his court to mix that with the word when he hears it.Yes, of course it is something a person does.
But it is not something a person can do if God doesn't give them faith (Eph. 2:8, Phil. 1:29, Rom. 12:3, 2 Pet. 1:1, John 10:26, etc.)