Ignorance of the truth leads to misconceptions. Many non-Catholics rejoice in attacking the members of the Catholic Church, quick at accusing them of not being Christians. If they only knew the truth!
The fact that Catholics were the first Christians is confirmed two ways:
1. First of all, most historians accept the fact that the Catholic Church was the first Christian community, such being confirmed from ancient texts.
2. Secondly, the modern practices of the Catholic Church are the closest to the practices of the apostles and early Christians. Some of those practices are:
A. When reading the writings of the early Christian writers, it is clearly seen that their doctrines and teachings are the same as those of today's Catholic Church.
B. The writers during the early days of the Catholic Church make reference to Bishops, priests, virgins living in communities (nuns), the Sacrament of Confession, the Baptism of infants, the Bishop of Rome as the Head of the Christian religion, and even reverence to the saints.
C. On the matter of Bishops, Pope St. Clement, quoting the Letter to the Corinthians 1, stated in A. D. 96, "For it will be no light sin for us, if we thrust out those who have offered the gifts of the bishop’s office unblamably and holily."
D. Regarding the Papacy, in A.D. 110, Saint Ignatius referred to Romans 1:1 when he said, "[From] Ignatius... to the church also which holds the presidency, in the location of the country of the Romans, worthy of God, worthy of honor, worthy of blessing, worthy of praise, worthy of success, worthy of sanctification, and, because you hold the presidency in love, named after Christ and named after the Father.”
E. On the subject of Holy Communion, St. Justin, Martyr, stated in his “First Apology”, A.D. 148-155, “This food we call the Eucharist, of which no one is allowed to partake except one who believes that the things we teach are true, and has received the washing for forgiveness of sins and for rebirth, and who lives as Christ handed down to us. For we do not receive these things as common bread or common drink; but as Jesus Christ our Savior being incarnate by God’s Word took flesh and blood for our salvation, so also we have been taught that the food consecrated by the Word of prayer which comes from him, from which our flesh and blood are nourished by transformation, is the flesh and blood of that incarnate Jesus.”
F. And on the matter of Infant Baptism, we read from Saint Hippolytus, The Apostolic Tradition 21:16, in A.D. 215, "Baptize first the children, and if they can speak for themselves let them do so. Otherwise, let their parents or other relatives speak for them”
G. Regarding the Sacrament of Confession, Origen, in the Homilies in Leviticus 2:4, in A.D. 248, we read, "[A filial method of forgiveness], albeit hard and laborious [is] the remission of sins through penance, when the sinner... does not shrink from declaring his sin to a priest of the Lord and from seeking medicine, after the manner of him who say, “I said, to the Lord, I will accuse myself of my iniquity.”
From the above, it is obviously clear that the practices of the Christian Church in its early days is no different than today's practices of the Catholic Church. This confirms that the Catholic Church was the very first Christian Church, the one instituted by Jesus Christ.
While the believers of thousands of different religions can claim to be "christians," they cannot claim to be "Catholics" who belong to the One, Holy, Catholic and Apostolic Church that was instituted on earth by Jesus Christ.