Why a Christian can only be a Catholic
A Christian is one who follows the true faith of Jesus Christ. In the Acts of the Apostles, we read that it was at Antioch that the followers of Christ were first called Christians.
Acts 11: 26 - "And they conversed there in the church a whole year, and they taught a great multitude, so that at Antioch the disciples were first named Christians."
Interestingly, it was also at Antioch, in the year 110, that the term "Catholic" was first applied to the Christian Church. This was done by the famous martyr of the ancient Christian Church, St. Ignatius.
St. Ignatius of Antioch, Epistle to the Smymaeans, Chapter 8, 110 A.D.- "Apart from the bishop, let no one do anything that pertains to the Church. The only true Eucharist is the one performed by the bishop or by him whom the bishop has appointed. Wherever the bishop is, there must be the congregation, just as wherever Jesus Christ is there is the Catholic Church.
In Greek, the term "Catholic" means universal. Thus, the one universal Christian Church came to be known as the Catholic Church. It makes sense that the terms Christian and Catholic became interchangeable, for the only Christian Church which existed from the beginning was the Catholic Church. Ignatius had a real connection to the original Christians. He was the third bishop of Antioch. Ignatius knew St. Polycarp who knew the apostle John himself.
Many think that being Christian means accepting everyone, being kind to everyone. Certainly being Christian involves a true charity toward all men. This means that you work and desire each man's salvation - each man's eternal happiness. First and foremost, however, being a Christian requires that one believe all the truths of Jesus Christ. It requires that one hear the one Church He established. For Jesus Himself declared that preaching the Christian faith (the Gospel) means "teaching them to observe all things whatsoever I have commanded you." (Matthew 28:19). In Matthew 18:17, we read that those who don't hear the Christian Church established by Jesus are to be considered as the "heathen and publican."
The true Christian faith has a real power. This power is of course identified with the miracles of its founder, the God-man, Jesus Christ. But the power of the Christian faith didn't dry up and disappear once Jesus ascended into Heaven. No, Jesus left that power with His Church. He left it not only in the miracles which He said some of His followers would perform (John 14:12), but in the supernatural protection and guidance which would sustain His visible Christian institution.
In Matthew 16:18-20, we read that this Christian Church structure was founded on the apostle Peter, who would be the first pope. This visible Christian structure would be an ongoing testament to Jesus Christ's power. It would guide Christians on the way of truth. It would also be necessary for salvation; for the Lord would add all who were to be true Christians to this one Christian Church (Acts 2:47).
One of the most moving episodes in Christian history - which illustrates the power of the Christian Church and its visible structure- involved Atilla the Hun and his invasion of Italy in 452. Attila the Hun was a fierce non-Christian emperor in the East. He was greatly feared by many in the Christian Roman Empire. In 447, Attila invaded the Eastern Empire. In 452, he was ready to invade Rome itself, the centre of the Christian Church.
With Atilla threatening the centre of the Christian Church, Pope Leo the Great, the undisputed leader of the Christian Church, faced him down. He went out to meet Attila. As Pope Leo went out to meet Attila, he was miraculously flanked by the apostle Peter. History tells us that St. Peter threatened Attila with death if he should proceed further. Attila was so frightened that he turned back. If Attila had not turned back, all of history might have been different. The leader of the Christian Church carried with him the supernatural protection of Christianity's founder, the Lord Jesus Christ.
After the initial establishment of the Christian Church, each century brought new challenges and trials for the Christian. Heresies would appear and lead many astray. Many who were Christians were separated by these heresies from the true Christian faith. Arianism was the most notorious of all the early heresies which threatened the Christian. It proclaimed that Jesus Christ was not true God, that He was not equal with the Father. Arianism spread wildly in the 4th century, causing countless people to lose the true Christian faith.
The two central dogmas of the Christian faith are the mysteries of the Trinity and the Incarnation.
The Trinity is the truth that there is one God in three divine persons: the Father, the Son and the Holy Ghost. Each divine person is God; yet there are not three Gods, but one God. Each person is a distinct person. The Sabellian heretics, for example, a group of false Christians, wrongly taught that each person is simply a different aspect of God. According to them, The Father and the Son are simply different elements of the same person. This heresy was condemned by the Christian Church. A Christian must believe that there are three divine persons, that each one is God, but that there is only one God.
The other central dogma of the Christian Church is the Incarnation. This is the truth that the Second Person of the Holy Trinity, the Son of God, became man. That is, Jesus Christ. He is one divine person, the second person of the Holy Trinity, with two natures. He is true God and true man.
[Taken from Most Holy Family Monastery] - (www.vaticancatholic.com)
When you read all that you can easily see why Catholics are Christians, and no one else, not the various Protestant sects, who like to think they are Christian and be called Christian, simply because they reject that one true Church founded by Jesus Christ Outside of which No one at all can be Saved.
What is the Church?
The (Catholic) Church is the visible society founded by Christ Himself, to continue on earth His work of teaching, sanctifying and ruling mankind, for their eternal salvation.
To whom did Christ give power to govern His Church?
Christ gave to St. Peter and the other apostles and to their lawful successors the power to teach, sanctify and rule the members of His Church.
Did Christ found only one Church?
Jesus Christ founded only one Church, for he declared: "There shall be one fold and one Shepherd (John 10:16).
Did Christ give to His Church any marks by which it can be clearly known?
Yes, Christ gave His Church four marks: He intended His Church to be one, holy, catholic and apostolic (John 10:16; Eph 5, 25-27; Matt. 24, 14: Eph. 2,20).
( From A Catechism of Catholic Doctrine - Official New Zealand Edition 1951 )
In this same Catechism we see demonstrated the heresy that had crept into various pre Vatican II publications and catechisms by the early 1950's, and before, in a subtle way, providing an exception to the dogma as it had been defined , on the necessity of belonging to the Church for salvation:
Must everyone belong to the Catholic Church?
Everyone must belong to the Catholic Church, and no one can be saved who, through his own fault, remains outside it.
Which allows, of course, for someone who has not heard of the Church, through "Invincible Ignorance," to save his soul Outside the Catholic Church, which is heresy!
Pope Eugene IV, Council of Florence, "Cantate Domino," 1441, ex cathedra:
"The Holy Roman Church firmly believes, professes and preaches that all those who are outside the Catholic Church, not only pagans but also Jews or heretics and schismatics, cannot share in eternal life and will go into the everlasting fire which was prepared for the devil and his angels, unless they are joined to the Church before the end of their lives; that the unity of this ecclesiastical body is of such importance that only for those who abide in it do the Church's sacraments contribute to salvation and do fasts, almsgiving and other works of piety and practices of the Christian militia produce eternal rewards; and that nobody can be saved, no matter how much he has given away in alms and even if he has shed blood in the name of Christ, unless he has persevered in the bosom and unity of the Catholic Church."
Note that "ex cathedra" statements refer to when a pope speaks infallibly from the Chair of St. Peter...it is heresy and mortal sin to deny an ex cathedra pronouncement of a pope, which is irreformable( unchangeable), since it constitutes the dogma that Christ revealed to the Church.
Pope Pius IX, First Vatican Council, Session 3, Chap.2 on Revelation, 1870, ex cathedra: "Hence, also, that understanding of its sacred dogmas must be perpetually retained, which Holy Mother Church has once declared; and there must never be a recession from that meaning under the specious name of a deeper understanding."