Summary: When preaching about the Unknown God in Athens, Paul made known these four basic truths: The Greatness of God, the Goodness of God, the Government of God, and the Grace of God.
The Unknown God
by Scott R. Bayles, preacher
Church of Christ
As Paul approached the great city of Athens, he came not as a sightseer, but as a soul-winner. He arrived with open eyes and a broken heart. Athens was in a period of decline in the early first-century. Though still recognized as a center of culture and education, the glory of its politics and commerce had long since faded. It had a famous university and numerous beautiful buildings, but it was not the influential city it once had been. The city was given over to a "cultured paganism" that was nourished by idolatry, novelty, and philosophy.
The Greek myths spoke of gods and goddesses that, in their own rivalries and ambitions, acted more like humans than gods; and there were plenty of deities to choose from! Someone once said that in Athens it was easier to find a god than a man. Paul saw that the city was "wholly given to idolatry," and it broke his heart. As was his custom, Paul spoke in the synagogue with the Jews, but he also witnessed in the marketplace (agora) to the Greeks. It didn’t take long for the philosophers to hear about this "new thing" Paul was preaching.
The Council of the Areopagus was responsible to watch over both religion and education in the city, so it was natural for them to investigate the "new doctrine" Paul was teaching. They courteously invited Paul to present his teaching at what appears to have been an informal meeting of the council on Mars’ Hill. After all, life in Athens consisted of hearing and telling new things, and Paul had something new! Let’s listen to what he said.
Acts 17:22-34 (NASB-u)
So Paul stood in the midst of the Areopagus and said, "Men of Athens, I observe that you are very religious in all respects.  For while I was passing through and examining the objects of your worship, I also found an altar with this inscription, ’TO AN UNKNOWN GOD.’ Therefore what you worship in ignorance, this I proclaim to you.  The God who made the world and all things in it, since He is Lord of heaven and earth, does not dwell in temples made with hands;  nor is He served by human hands, as though He needed anything, since He Himself gives to all people life and breath and all things;  and He made from one man every nation of mankind to live on all the face of the earth, having determined their appointed times and the boundaries of their habitation,  so they would seek God, if perhaps they might grope for Him and find Him, though He is not far from each one of us;  for in Him we live and move and exist, as even some of your own poets have said, ’For we also are His children.’  Being then the children of God, we ought not to think that the Divine Nature is like gold or silver or stone, an image formed by the art and thought of man.  Therefore having overlooked the times of ignorance, God is now declaring to men that all people everywhere should repent,  because He has fixed a day in which He will judge the world in righteousness through a Man whom He has appointed, having furnished proof to all men by raising Him from the dead."