a rationalist should acknowledge their irrationality, to do otherwise would be to irrational.
All you did was show that your argumentative skills were better.
His intial belief mentioned souls, and i dont think you ever did.
I'd like to see some sort of testability for souls :)
As to your reply of possibly proving his religion false, if he was better at arguing, he may have replied that at the least it might prove his understanding of religion false.
And of course its not as if you have created an AI.