Christianity has a central core message and event that is vital. Without it, there is no Christianity whatsoever. All the faith, works, laws, worship, etc. are worthless and meaningless without it. Jesus Christ crucified and risen from the dead is that center. Jesus' life, death, resurrection, ascension, and return give meaning to the faith (1 Corinthians 15:1-7, 14, 17-20). As Peter explains what the events of Pentecost mean, he cannot do it apart from the death and resurrection of Jesus of Nazareth.