Good study. I agree with this preacher that Paul was not wrong in preaching that message in Athens. I heard not long ago a preacher who said that Paul succombed to the temptation of intellectualism and did not preach simply Christ and the cross as he did in Corinth. But he preached Christ, the Word didn't say he was wrong and God blessed the preaching with saved persons!
Importance of Scriptures. It is true: in the Scripture we have all what is needed to know for our salvation. It is God's revelation of Himself, of our condition and our salvation. People who reject the Scriptures reject God's salvation.