Look at how the discussion elivens when Paul suggests that an event illustrating the miraculous suspension of the laws of physics provides evidence for his message. The church representative is there to referree. The church member says “why then, why not now”. The discussion leader say “how now, not why not now”. Signs and wonders in the old testament happened in order to show evidence for the God of the Bible. They happened in the new testament, as we see in Acts 14, to show evidence for the new gospel message. They happen now in order to encourage the faithful and challenge the skeptical.