Nothing "began at Pentecost".
The "day of Pentecost" recorded in the book of Acts was continuation of ALL that God was doing with Israel, just like Peter said:
Act 2:16 KJV But this is that which was spoken by the prophet Joel;
Since you don't understand any of this, it makes perfect sense that you would say something this dumb.
Once again, Paul taugh "
according to my gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began". Romans 16:25.
Your problem is that YOU do NOT know Jesus Christ ACCORDING to the revelation of the mystery kept secret since the world began. This means that YOU are out of the will of God and His plans today.
Coming from a Christ denier, this is high praise!