It may be surprising to say that the Catholic Church is apostolic because for two thousand years her members had believed in the papal primacy. In ordinary language, “apostolic” means deriving from the Apostles. However, the Church’s apostolicity would have disappeared by the end of the first century, except for the papal primacy. It was the supreme authority of the Bishop of Rome over the bishops in the Church which has preserved her authentic, apostolic character. Whenever bishops separate themselves from the authority of the successors of St. Peter, they inevitably deprive the Church of more or less of her apostolic character. This fact is especially evident in the departure from Christ’s teaching which inevitably followed an episcopate separated from Roman unity.
There is another profound definition of the title “Apostolic” applied to the Church founded by Christ. This is the historical fact that sacred orders, possessed by bishops and priests, are traceable, generation after generation, back to Christ’s ordination of the Apostles at the Last Supper. The power which He conferred on the Apostles on Holy Thursday night has been passed on from them to every bishop, and every priest, in the world today.
The implications of this truth are beyond human explanation. Except for this apostolic succession from the eve of Good Friday, there would be no validly ordained bishop or priest on earth. Except for this apostolic succession, there would have been no Real Presence, no Sacrifice of the Mass, and no Holy Communion as the principal source of grace for the human race over the past two thousand years.
More still, except for this apostolic succession, there would be no remission of sin in the sacrament of penance and no preparation for death in the sacrament of anointing.
Finally, except for the Church’s apostolic succession, what Christ revealed during His visible stay on earth would not have been preserved as the treasury of truth on which our destiny depends.
Nowadays, there are so many mystics and seers and visionaries, all claiming to have received revelations from God, that we better have some divinely authorized norms for sifting objective truth from subjective imagination. We have these norms. They are the public revelation, completed with the death of St. John, the last Apostle. Whatever conforms to this apostolic heritage is true. Everything else is a mirage.