"All Churches are the same. I don’t need to attend any church to worship God. I can pray and read the Bible in my own room."
To profess belief in Jesus Christ not only obliges the Christian to believe in His person, but to believe in and follow what He established to continue His work of salvation in the world after His ascension. That Our Lord Jesus Christ intended to establish a Church of His own and require the faithful to obey it is clear from Sacred Scripture:
"...and on this rock I will build my Church..." (St. Matt. 16, 18). The Church belongs to Christ as it was founded by Him while He was still on earth; it is not a man-made institution established centuries later bearing the name of the particular heresiarch who spawned its existence.
This Church is to be a visible organization:
"A city built on a hill cannot be hid" (St. Matt. 5, 14). Being visible, Christ’s Church possesses a hierarchical authority to govern it (St. Luke 6, 13) which is invested with His own mission (St. John 20, 21) to teach (St. Matt. 28, 20) to rule (St. Matt. 18, 17-18) and to sanctify the faithful (St. John 15, 16).
Christ appointed St. Peter as head of this visible and hierarchical Church on earth:
"You are Peter, and on this rock I will build my church" (St. Matt. 16, 18).
As head, St. Peter is invested with Christ’s own authority to rule and govern:
"I will give you the keys of the kingdom of heaven, and whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven" (St. Matt. 16, 18-19).
Those who purport to ignore Christ’s Church through their own disobedience no longer belong to its unity:
"if he refuses to listen even to the church, let him be to you as a Gentile and a tax collector" (St. Matt. 18, 17).
To ignore the Church, one effectively ignores Christ:
"He who hears you hears me, and he who rejects you rejects me" (St. Luke 10, 16).
Despite the disobedience and protestations of its enemies and the rebellious, Christ will protect His Church so that "the gates of hades will not prevail against it" (St. Matt. 16, 18), lasting "always, to the end of the age" (St. Matt. 28, 20).
Our Lord not only took pains to establish His Church, but endowed it with four outstanding visible signs or "marks" which are intrinsic only to it: One, Holy, Catholic and Apostolic.
One
"I will build my Church" (not Churches) (St. Matt. 16, 18). Protestantism is not one united body in doctrine and discipline, but a series of disparate organizations antagonistic not only to Catholicism but also often to each other.
"...one flock, one shepherd" (St. John 10, 16). The central authority of the Pope of Rome has kept the Catholic Church united in doctrine and discipline since the days of the Roman Empire. Protestantism continues to splinter with the advent of each new self-appointed "prophet" who claims to hold the true meaning of Sacred Scripture.
Holy
"And for their sakes I sanctify myself, so that they also may be sanctified in truth" (St. John 17, 19).
The true Church will be holy in Her founder, teachings and worship. There is no guarantee that all its members will practice what She preaches as is gathered from Our Lord’s images of the sower of the seed (St. Matt. 13, 18-23), the net enclosing the fish (St. Matt. 13, 47-52), and the sheep and the goats (St. Matt. 25, 31-46). The survival of the Catholic Church despite the examples of "bad Popes" only reinforces the fact that the holiness of the Church derives from Christ and Him alone.
Catholic
"Going therefore and make disciples of all nations..." (St. Matt. 28, 19).
Remaining essentially one and the same, the Church adapts to all times, places and people. No nation or race is excluded from Her fold, no language from proclaiming Her Gospel. Those who assert that the true believers are only white and Anglo-Saxon limit the redeeming power of Christ’s Precious Blood.
Apostolic
The true Church will trace its history and doctrine right back to the Apostles themselves: "I am with you always..." (St. Matt. 28, 20). It was not established in 1517, 1534, 1540 or in the nineteenth century. It must have existed since the Apostles, exist now, and continue until the end of the world.
Only the Roman Catholic Church can show itself to be One, Holy, Catholic and Apostolic.
The Fathers:
St. Clement of Rome, Letter to the Corinthians (C. 96 - 98 A.D.):
"The Apostles received the gospel for us from the Lord Jesus Christ; and Jesus Christ was sent from God. Christ, therefore, is from God, and the Apostles are from Christ. Both of these orderly arrangements, then, are by God’s will. Receiving their instructions and being full of confidence on account of the resurrection of Our Lord Jesus Christ, and confirmed in faith by the word of God, they went forth in the complete assurance of the Holy Spirit, preaching the good news that the Kingdom of God is coming. Through countryside and city they preached; and they appointed their earliest converts, testing them by the spirit, to be the bishops and deacons of future believers. Nor was this a novelty: for bishops and deacons had been written about a long time earlier. Indeed, Scripture somewhere says: ‘I will set up their bishops in righteousness and their deacons in faith.’"
St. Clement of Alexandria, Miscellanies (Post 202 A.D.):
"From what has been said, then, it seems clear to me that the true Church, that which is really ancient, is one; and in it are enrolled those who, in accord with a design are just...We say, therefore, that in substance, in concept, in origin and in eminence, the ancient and Catholic Church is alone, gathering as it does into the unity of the one faith which results from the familiar covenants, - or rather, from the one covenant in different times, by the will of the one God and through the one Lord, - those already chosen, those predestined by God, who knew before the foundation of the world that they would be just."
St. Cyprian of Carthage, Letter to Florentius Pupianus (254 A.D.):
"There speaks Peter, upon whom the Church would be built, teaching in the name of the Church and showing that even if a stubborn and proud multitude withdraws because it does not wish to obey, yet the Church does not withdraw from Christ. The people joined to the priest and the flock clinging to their shepherd are the Church."
St. John Chrysostom (+407 A.D.), De Incomprehensibili 3, 6:
"You cannot pray at home as at church, where there is a great multitude, where exclamations are cried out to God as from one great heart, and where there is something more: the union of minds, the accord of souls, the bond of charity, the prayers of the priests."
Catechism of the Council of Trent (1566):
The true Church is also to be recognized from her origin, which can be traced back under the law of grace to the Apostles; for her doctrine is the truth not recently given, nor now first heard of, but delivered of old by the Apostles, and disseminated throughout the entire world. Hence no one can doubt that the impious opinions which heresy invents, opposed as they are to the doctrines taught by the Church from the days of the Apostles to the present time, are very different from the faith of the true Church.
Catechism of the Catholic Church (1992):
"Outside the Church there is no salvation"
No. 846: How are we to understand this affirmation, often repeated by the Church Fathers? Reformulated positively, it means that all salvation comes from Christ the Head through the Church which is his Body:
Basing itself on Scripture and Tradition, the Council teaches that the Church, a pilgrim now on earth, is necessary for salvation: the one Christ is the mediator and the way of salvation; he is present to us in his body which is the Church. He himself explicitly asserted the necessity of faith and Baptism, and thereby affirmed at the same time the necessity of the Church which men enter through Baptism as through a door. Hence they could not be saved who, knowing that the Catholic Church was founded as necessary by God through Christ, would refuse either to enter it or to remain in it.
No. 847: This affirmation is not aimed at those who, through no fault of their own, do not know Christ and his Church:
Those who, through no fault of their own, do not know the Gospel of Christ or his Church, but who nevertheless seek God with a sincere heart, and, moved by grace, try in their actions to do his will as they know it through the dictates of their conscience - those too may achieve eternal salvation.
No. 848: Although in ways known to himself God can lead those who, through no fault of their own, are ignorant of the Gospel, to that faith without which it is impossible to please him, the Church still has the obligation and also the sacred right to evangelize all men.