Mama Younger, the strong matriarch of the extended Younger family all living in one tiny, slum-like apartment, is a devout, if traditional, Christian woman. She rules the household, including prohibiting the Lord's name from being taken in vain, for instance. Her progressive-minded daughter Beneatha, however, wants to train to be a medical professional, and rebels against her mother’s more traditional values.
As the stress in the household grows, Beneatha has an argument with Mama Younger, crying out,
I'm just tired of hearing about God all the time. What has He got to do with anything?... I'm not going to be immoral or commit crimes because I don't believe. I don't even think about that. I just get so tired of Him getting the credit for things the human race achieves through its own effort. Now, there simply is no God. There's only man. And it's he who makes miracles.
In other words, Beneatha puts her faith in a man (or woman!) to make decisions that determine his own fate. This sets up the ultimate decision the family makes, to move into a house in the white neighborhood and become part of the tide of change that is coming along with the American Civil Rights Movement.