Does 1 Corinthians 12:3 mean that no one can come to believe in Christ apart from a special revelation direct from God? Are there Gnostic and/or Calvinist implications?

Is it impossible for God to exist?

Are there any good alternative theories to the single authorship of Luke-Acts? 

I notice that John the Baptist was executed by Herod, while Jesus was executed by Roman authority, why the difference?