Some quotations from Tim Keller, Making Sense of God: An Invitation to the Skeptical:
“The declaration that science is the only arbiter of truth is not itself a scientific finding. It is a belief.” (35)
“Russian philosopher Vladimir Solovyov sarcastically summarized the ethical reasoning of secular humanism like this: ‘Man descended from apes, therefore we must love one another.’ The second clause does not follow from the first. If it was natural for the strong to eat the weak in the past, why aren’t people allowed to do it now? . . . Given the secular view of the universe, the conclusion of love or social justice is no more logical than the conclusion to hate or destroy. These two sets of beliefs—in a thoroughgoing scientific materialism and in a liberal humanism—simply do not fit with one another. Each set of beliefs is evidence against the other. Many would call this a deeply incoherent view of the world.” (42–43)
“The humanistic moral values of secularism are not the deliverances of scientific reasoning, but have come down to us from older times . . . they have a theological history. And modern people hold them by faith alone.” (43).
“If you say you don’t believe in God but you do believe in the rights of every person and the requirement to care for all the weak and the poor, then you are still holding on to Christian beliefs, whether you will admit it or not. Why, for example, should you look at love and aggression—both parts of life, both rooted in our human nature—and choose one as good and reject one as bad? They are both part of life. Where do you get a standard to do that? If there is no God or supernatural realm, it doesn’t exist.” (47–48)
“While there can be moral feelings without God, it doesn’t appear that there can be moral obligation.” (178)
“A moral judgment about something can never be made apart from an examination of its given purpose. . . . How, then, can we tell if a human being is good or bad? Only if we know our purpose, what human life is for. If you don’t know the answer to that, then you can never determine ‘good’ and ‘bad’ human behavior.” (186–87)
“If your premise that there is no God leads most naturally to conclusions you know are not true—that moral obligation, beauty and meaning, the significance of love, our consciousness of being a self are illusions—then why not change the premise?” (227)