Because it is true ( John 14 v 6 )

                          A  man who was an unbeliever attended church
                          the minister spoke to him, from time to time.One
                          morning at the communion service he noticed the
                          man taking communion. The minister asked him why
                          he  had taken communion, the man replied, because 
                          it is true.
                                                   Luke 1 v 1-4.
                                                1 Corinthians 15 v 1 - 8.