We don't have these signs today. And it is probably for the best. The world has changed for Christians today in modern America. And, the changes make our job more difficult and easier than Christians of 20 centuries ago. Though many need to be taught truth, most today will admit the existence of God, of Jesus, of the Bible as authority.
Many folks have faith in their families and background.
Christianity is a watered down element of our culture. Paul might be confused about the change of rules and the shift of playing field, but he, in time, would be just as effective today as then. The Lord still works through us.