The staff member or other close family friend who obviously knew whatever she said about Nancy answered that issue at the close of her segment. She disagrees with you.
i still say that she has a lot of faith or she would not have stood by her husband through his presidency, let alone the Alheizmer years.
Also if these services are any indication and you watched her body language, the mentioning of God and her husband brought 'near' smiles.
Thirdly, a man and woman joined together in matrimony need to have the third person of that relationship there all the time -- that third person is God. I really do think that God blessed both of them with belief.
She differed from her husband on several issues, but she has a belief in God.