Paul and Barnabas finally realize what is going on they attempt to calm the crowd (verse 14-18). Paul explains who they are and what God they represent. This is an opportunity to see how Paul speaks to completely non-Jewish audience, in complete contrast to the synagogue sermon in chapter 13. Later Paul speaks to a pagan crowd in Acts 17, but in that context the crowd is rather intellectual and philosophical. In this case, Paul is addressing a group of average people, ones who can be described as real pagans since they worship Zeus with sacrifices. It is unlikely that the Stoic and Epicureans on Mars Hill would have participated in this sort of thing!
When people discuss Mars Hill these days, it is usually in the context of preaching the gospel as Paul did in Acts 17. We ought to engage culture and use the elements of culture in order to share Jesus with the unsaved world. I agree, however, I am not sure that Paul would, based on this sermon to a crowd of pagans. Paul is not seeker-sensitive, nor does he embrace their culture in order to preach the gospel, and in no way does Paul weaken the Gospel before this pagan crowd.
There are several things we need to see in this sermon. For this list, I am following Eckhard Schnabel, Paul the Missionary, 164-6.
First, Paul states emphatically that the gods worshiped in Lystra are worthless (14:15). You have to see this scene in your mind in order to fully understand the impact of Paul’s statement that these gods are worthless. There are priests standing right in front of him, about to sacrifice bulls to Zeus, and a large crowd of people are about to participate in that worship of Zeus. Paul is not making this statement from a safe distance (from his academic office preparing a lecture, for example). He is telling a priest of Zeus that Zeus is nothing at all.
Second, since these idols are worthless, the people of Lystra ought to turn away from them (14:15). This is culturally shattering. Schnabel points out that this means that the people of Lystra ought to no longer prayer to Tychos, the god of luck, before tossing the dice. No more praying to Asclepius, the god of healing, when they are sick. No more praying to Artemis, the goddess of childbirth, for the protection of a mother and child before a birth. The entire culture of the Greco-Roman world was integrated with the worship of gods, yet Paul says to turn away from them since they simply do not exist.
Third, if they turn from the worthless gods, they ought to turn to the living God. This is the demand of the Gospel, they must make a decision to worship the real God.
Fourth, that living God is the creator and preserver of life. Rather than point out the many acts of God in the Hebrew Bible, Paul uses God’s preservation of men through the giving of rain and crops as an example of his power. In fact, this “general revelation” is God’s witness to the world, drawing the pagan nations to a knowledge of God (cf., Romans 1:18-20).
Face with a potentially hostile pagan crowd, Paul does not give up on the biblical story in this sermon. He begins with God’s creation and provision. He says that he represents the creator, something which this group can understand within their own worldview, but Paul uses the language of Genesis (the heaven, the earth, and the sea, along with everything in them.)
This speech does not have the desired effect: the crowd still wanted to sacrifice to Paul and Barnabas as gods. It is only with “difficulty” that Paul is able to persuade the crowd to stop the sacrifices. Perhaps this is a hint that out best efforts to engage culture will encounter “great difficulty.” However, this is no reason to give up on that engagement.