One objection to apologetics runs as follows: “Only God can effectively call someone to faith”. Well, amen and hallelujah. But how does God call us? Typically, through his word; and it is astonishing how often God’s word reasons with unbelief. For example Paul opens his chief theological statement, the book of Romans, with a critique of idolatry and polytheism. The creator’s eternal power is revealed through the natural world; the author of this creation must be far greater than anything in the created realm. Yet, even though everyone instinctively searches for God, pagans worship with pieces of wood and stone. This is foolishness, for they should know that something even more beautiful lies behind the beauty of nature. .
Paul makes a similar argument to the Athenians in Acts 17. The ‘world and everything in it’ reflects the power of one creator. If everything in this world depends on a creator, then it follows that the creator cannot depend on anything in nature. It is madness, then, to bring food to idols as a means of honouring the divine. Furthermore, it is absurd to suggest that anything fashioned by human hand could contain or convey the majesty of the creator. These arguments would have been familiar to the Stoic and Epicurean philosophers of Athens. They might even have been sympathetic to Paul’s argument that because all men searched for the same thing, it was more reasonable to believe in one creator. Creation, after all, testified to one designer and one providential plan. 
Of course, if the gods of the pagans cannot adequately account for creation, neither can atheism. Atheism is on trial when Paul writes in Romans and preaches in Athens. Sadly, the philosophers cut Paul off when he mentioned the resurrection; the intellectual elites of Athens were more interested in fashions than truth, as Luke makes clear. But it was a tragic moment when Paul was silenced at the Areopagus, for the reader of Acts knows that he had excellent evidence for the resurrection. Acts not only appeals to the eyewitness testimony of the apostles; Paul could ask the Roman procurator Festus and King Herod Agrippa II to consult the public record! Presumably, the Jewish authorities had some difficulty in accounting for facts like the empty tomb!
When we are explaining the Gospel we have an obligation to let the Scriptures speak; and God’s word contends that unbelief makes no sense. God’s call does not bypass our brains. So we must follow Paul’s example and argue passionately for the Gospel. Without the doctrine of creation man cannot make sense of his world; without the doctrine of the Fall he cannot make sense of himself. Without God’s Law he has no meaning; without God’s Gospel he has no hope. This is not a quest for academic credentials; we are not seeking intellectual respectability. But it remains the duty of every evangelist, every preacher, every pastor, and every Christian, to do all that they can to persuade the unbeliever of the truth of the Gospel. And that means apologetics!
 See James Barr Biblical Faith and Natural Theology (Clarendon:1994) pp21-80
 See James Dunn Beginning From Jerusalem: v. 2 Christianity in the Making (Eerdmans:2009)pp683-686; Bruce W. Winter, “Introducing the Athenians to God: Paul’s failed apologetic in Acts 17?” Themelios 31.1 (October 2005): 38-59