The atheist yells back, "There is no God".
She does this every morning with the same result.
As time goes on, the lady runs into financial difficulties and has trouble buying food.
She goes out onto the porch and asks God for help with groceries, then says
"Praise the Lord".
The next morning she goes out onto the porch and there's the groceries she asked for, and of course, she shouts
"Praise the Lord!!!".
The atheist jumps out from behind a bush and says,
"Ha, I bought those groceries - there is no God".
The lady looks at him and smiles, she shouts
"Praise the Lord, not only did you provide for me Lord, you made Satan pay for the groceries!!"