Romans 1:16-32

v16-18: Why might we be ashamed of the gospel?  Because "the one whose Gospel it is was hanged on a tree," "its message was plain and contained little to commend it among scholars," "Its professors were insignificant and despised," "it was spoken against everywhere." Yet we must confess it because only this message saves and declares us right with God.

v18-32: Paul describes human sinfulness as ungodliness and unrighteousness.  Ungodliness is against the laws found in the first four commandments, and unrighteousness is against those found in the remaining six commandments.