Athens was a city full of idols. Paul preached about the one true God.
1. A town like Athens - centre of culture and learning. V16 - Paul was distressed at the idolatry. He speaks to the leaders and philosophers (v18). Paul was called a 'babbler'. v21-It was going to be hard work for Paul. The people were not searching for truth. (compare the people of Berea, v11). They didn't want to change - the Gospel was just another idea to them.
2. God is not served by human hands. (v24). He doesn't need us, but the true God gives/offers all people life and a relationship with Himself (v27). Our default position is for life to revolve around us. God serves.
3. God commands repentance. (v30-31). Hearing and ideas are not enough - its about the truth and it must be submitted to. The Athenians were ignorant of the real truth. Time of ignorance is past - because of Christ and the proof of His resurrection.