"The fool hath said in his heart, 'There is no God.'" The 16th century translation of the opening words of Psalm 14 has often been taken to mean "atheists are idiots". The words mean nothing of the kind, but the misunderstanding is a good illustration of the problems when Christians talk to non-believers.
Leaving aside frivolous points (hearts pump blood and do not speak, the male sex has no monopoly when it comes to foolishness), there are two places where we need to look at the face value of these words. There is the question of who says them, and of what they say.
'Fool' is not the best translation of the Hebrew word nabal, which carries two ideas: a lack of wisdom and a disregard for upright behaviour. Where "the fear of the LORD is the beginning of wisdom", being intelligent is not the same as being wise, and being a nabal, or fool, does not mean lacking intellectual gifts or common sense, but churlishly disregarding decent behaviour or God's laws. 'Reckless hearts' is the phrase one translation uses.
And saying "There is no God" does not means saying that God does not exist, any more than saying "There is no justice" means justice does not exist. The meaning is that there are reckless people around who disregard God.
This meaning is confirmed by the second half of the first verse of the psalm. "They are corrupt, they do abominable deeds; there is no one who does good." And this raises another problem when we talk to non-believers. We must not only be clear what words mean, but we must be careful not to lift them out of their context.
The idea of using single verses as proof texts is one that has a long history, and is embedded in the Bible itself. "Behold, a virgin shall conceive." "The voice of one crying in the wilderness...." Quotations like these illustrated and reinforced what later writers in the New Testament were trying to express, but it is important to realize that a 'proof text' provides evidence and illustration, and even a hundred such texts do not necessary demonstrate what is true in a different context. (Nor does discrediting the text disprove what it illustrates!) Your diary and your calendar will tell you when the sun rises, but most people agree that in fact the sun stays still and it is the earth which revolves.
The problems of what words mean and in what context make it very difficult for Christians and non-Christians to speak the same language - indeed, it is hard enough for Christians from one tradition to get their point across to those of a different one! Atheists scoff at the thought of God making fish and birds in a single day (Gen. 1:20-23), making the sun go backwards (2 Kings 20:11), of fishes swallowing reluctant prophets (Jonah 1:17), of dead people coming out of their tombs (Matt. 27:52). On the other hand, Christians often forget that Darwin wrote about the origin of species, not the origin of life.
The point of Genesis 1 is not to explain how the world was made, but to show how the sun, the moon, trees and wild animals were not divine beings to be worshipped, but were subordinate to God, who was greater than them all. Jonah and the fish, Daniel and the lions are not stories from a newspaper report: their object is to carry a message. The atheist who scoffs and the Christian who reads with attention are not thinking in the same terms.
In the same way, Darwin's work contains acute observations of the 14 species of finch he found on the Galapagos Islands. It is not a recipe book for a set of reproducible experiments, and while it may suggest useful lines of thought about how horses and donkeys are different species, his work will tell you less about the evolution of animal families - horses and cows, for instance, and next to nothing about how the horse and the grass it eats came to co-exist in a single environment. That is not what it is about.
Faith is not about the origins of horses. It is about the way we lead our lives, about the power to free ourselves from the rat-race of selfishness and sin. It is about turning us all, no matter what our intellectual abilities may be, from the way of foolishness into the way of wisdom.
HD