Claiming atheism is exactly what my daughter’s “wife” has done.
Just keep praying for your daughter -- and for the salvation of the "wife".
I am reminded of the last conversation I had with my girlhood best friend, who had fallen away from the church in young adulthood when she married a domineering secular guy. When in her 60s she had terminal cancer, I asked her what she thought would happen after she died; and of course she said, "You're just gone. That's all."
I said, "What if you're wrong? What if what you learned in Sunday School really was right, and your rejection of God will have eternal consequences? What if you don't get to say how it is, but there is a stronger force than you who will decide what happens to your soul?" At this point, tears were running down my face. "If there's a heaven, I don't want you to be missing from my eternal life, my friend!"
She said, "I'd go back to church, but my husband will kill me!"
To which I incredulously replied, "But you're already dying, girl! You've given up your religion for him for all these years. He can do this last thing for you, drive you to church."
Next I encountered them was at her funeral (we lived far apart). They both had formed a relationship with a church and pastor, and although her husband remained unconverted, he did arrange a beautiful, reverent Christian funeral for her that was very well attended.
I thanked him; and I thanked Him.