U Chicago prof here:
First of all, Weikart doesn’t recognize the irony of his implication that “See? Atheists believe in fairy tales. They’re just as bad as we are!” Well, he might respond that his Christianity is certainly not a fairy tale, because it’s not only based on empirical truths like Jesus Man being resurrected, but also gives us an objective morality and an objective purpose in our lives. But why is his Christianity true and Islam and Hinduism, which inspire different purposes, false?
But step back and consider the question: what is that meaning and purpose? As we know, one can discern an infinite number of meanings and life-purposes from just the Bible alone, for its “objective” lessons are debatable. Is the lesson to do what God tells us to do? In that case, let us stone adulterers and kids who curse their parents, and let us forsake our families and homes to follow Jesus. And how do we follow Jesus? Does our purpose include fighting against abortion and gay marriage, not to mention the Evil Materialism of Evolution? (To my mind, any purpose that makes its adherents tell lies about science, as does the Discovery Institute and Weikart himself, is a nefarious purpose.) Discerning purpose from the Bible is at best an act of pure subjectivity, and one that comports, as Plato realized, with a pre-existing and non-Goddy set of values.
And which scripture should the faithful pick to give them purpose, and which faith should they follow? What about Muslims? The Qur’an and its interpretations can lead to purposes completely different from those of Christians, and include exterminating unbelievers and scrupulously following the dictates of the Holy Book itself—something that Christians have learned to turn into malleable metaphors. More.
See also: Do atheists find meaning in life from inventing fairy tales?