No One Can Say "Jesus is Lord" Except in the Holy Spirit

In this Ask Pastor Tim, Tim responds to the following question:

So many people around the world say that Jesus is Lord and are probably not saved. I just don't understand 1 Corinthians 12:3 which says, "Therefore I want you to understand that no one speaking in the Spirit of God ever says 'Jesus is accursed!' and no one can say 'Jesus is Lord' except in the Holy Spirit." Please explain why many are not saved yet they say Jesus is Lord. I'm just confused.