Christianity needs the Catholic Church
Christianity needs the Catholic Church to be the "Anchor" that connects Christianity to the original teachings passed down by Jesus Christ.
I am a Catholic, which means that I am a Christian, contrary to what other Christians may believe. I believe that I am a member of the Church that Jesus Christ instituted 2000 years ago. Since then, Christianity has been splintered into thousands of churches/denominations that all claim to teach what Jesus taught. I think of these groups as "incomplete Christians." This is not meant to be a derogatory statement. It just means that these other Christian groups do not have the fullness of the faith. They don't take advantage of everything that Jesus offered to his believers (like all seven Sacraments, 2000 years of Tradition, and a Magisterium that faithfully and infallibly interprets Scripture). Any faith formation that I had prior to becoming Catholic was Protestant.
Simon Peter said in reply, “You are the Messiah, the Son of the living God.” Jesus said to him in reply, “Blessed are you, Simon son of Jonah. For flesh and blood has not revealed this to you, but my heavenly Father. And so I say to you, you are Peter, and upon this rock I will build my church and the gates of the netherworld shall not prevail against it. I will give you the keys to the kingdom of heaven Whatever you bind on earth shall be bound in heaven; and whatever you loose on earth shall be loosed in heaven. Mt 16:16-18
This is the passage from the Bible where Jesus instituted the Universal or Catholic Church. The Church that he began. But, as I stated above, the Holy Spirit is not confined to only Catholics.
Scripture is our supreme and final authority on all matters; [the Bible] includes all 66 books of the Old and New Testaments; He [God] sent his Son to bear the full penalty for humanity’s sin ... Jesus Christ suffered and died in the place of sinners, thus satisfying the Father’s just wrath against human sin; We believe justification is a judicial act of God’s grace wherein he acquits a person of all sin and accepts that person as righteous in his sight because of the imputed righteousness of Christ. Justification is strictly a work of God’s grace, apprehended through faith alone and solely on the account of Christ.
I admit that I have not included parts of these statements where atonement is mentioned. But Jesus was not punished for our sins. He gave himself freely as an atonement for our sins like a sacrificial lamb. There is a big difference. RTB does mention atonement, but only after stating that Jesus was punished. I use RTB as an example of most Protestant thought. We are saved by faith through by God's grace., but not by faith alone. How do we receive God's grace? Jesus gave us Baptism, Confirmation, the Eucharist, Confession, Anointing of the Sick, Matrimony, and Holy Orders.
Just like the Holy Spirit, anyone can receive God's grace, but the Sacraments are efficacious signs of grace, instituted by Christ and entrusted to the Church, by which divine life is dispensed to us through the work of the Holy Spirit. They bear fruit in those who receive them with the required dispositions (Catechism of the Catholic Church 1134). For example, I can ask Jesus Christ to forgive me, and he might, if I have contrition. But if I go to Confession with the appropriate disposition/contrition and the priest absolves me of my sins, then I know that I have been forgiven.
[Jesus] said to them again, “Peace be with you. As the Father has sent me, so I send you." And when he had said this, he breathed on them and said to them, “Receive the Holy Spirit. Whose sins you forgive are forgiven them, and whose sins you retain are retained.” Jn20:21-23
By the way, my Catholic Bible contains 73 books. Martin Luther conveniently left out the books with which he disagreed. Also, who was responsible for creating the original Canon of the Bible? The Catholic Church in the 4th Century after Christ.
Worship is at the heart of religion, and sacrifice is at the heart of worship. When Catholics attend Mass and receive Communion, they are participating in the sacrifice of Christ and receiving Christ's body and blood. The closest thing Protestants have to this is an altar call.
Does the Holy Spirit operate outside the Catholic Church? Of course! Does God offer his grace to Protestants as well as Catholics? Of course! However, Catholics have access to the fullness of Faith, and the original Church that was instituted by Jesus Christ. We have a Priesthood, a Vicar of Christ (the Pope), a 2000-year-old Tradition, a Magisterium, and Scripture! We get the whole enchilada!
Christianity needs the Catholic Church to be the "Anchor" that connects Christianity to the original teachings passed down by Jesus Christ. Should a person not you want to have access to all that Christ has to offer and know that you are part of the Church that Christ himself instituted? Even if you are not Catholic, you can still tap into what the Catholic Church has taught for centuries and anchor yourself to the original Christian Church. It's all still there.