“And suddenly a sound came from heaven like the rush of a mighty wind, and it filled all the house where they were sitting.  And there appeared to them tongues as of fire, distributed and resting on each one of them” (Catholic edition RSV, Acts 2:2.3)

So was God’s irresistible spiritual power let loose on the world.  The living Spirit of God was given of whom Our Lord had told his disciples, ”…he dwells with you, and will be in you” (Catholic edition RSV, John 14:17), and the effect was immediate and startling.  From that moment they were different men.

Peter – rash, violent and unstable – now lived up to the nickname which Our Blessed Lord had given him and he became as strong and reliable as a rock.  And the same was true of the other Apostles: their own failings and shortcomings were replaced by the personal qualities of Our Lord himself.  For with the gift of the Holy Spirit, Our Lord came to them in all his risen power as he had promised them, “I go away, and I will come to you” (Catholic edition RSV, John 14:28).

The contrast between what they had been and what they became is plain enough to us as we read first the Gospels and then the Acts of the Apostles.  But to those who actually knew them at the time, they must have seemed almost unrecognisable.  And the same transformation of character was effected in their converts.  It was in reference to this observed fact that St Paul said, “…if any one is in Christ, he is a new creature; the old has passed away, behold, the new has come” (Catholic edition RSV, 2 Corinthians 5:17).

Thus the indwelling of the Holy Spirit not only transformed the characters of the Apostles but their whole outlook as well.