Dear Mohammad:

Thank you for asking the questions. I'll answer them one-by-one:

1. Why do we need a priest to hear our confessions?

The Sacrament of Confession was established by Christ and is outlined in the Bible.

1 John 5:16-17 -- If anyone sees his brother commit a sin that does not lead to death, he should pray and God will give him life. I refer to those whose sin does not lead to death. There is a sin that leads to death. I am not saying that he should pray about that.

All wrongdoing is sin, and there is sin that does not lead to death. 

These verses teach us that while all sins are sins that some sin is not "mortal" and some sin that are mortal. The word mortal comes from the Latin, morte, meaning death. That is, some sins are so serious (mortal sin) that we lose sanctifying grace (the type of grace that saves us). Losing Sanctifying grace causes spiritual death. If we die without this state of grace then we go to hell.

With less serious sin, venial sin (that does not lead to spiritual death), we do not lose sanctifying grace, but we damage our relationship with God.

Perhaps this analogy can illustrate the difference between mortal and venial sin:

With an electrical lamp a cord connects the lamp to an electrical outlet. The electricity flows freely to the light bulb and the light bulb turns on and shines perfectly. This condition is a State of Grace (sanctifying grace).

We can damage this electrical connection by a short in the electric line. In this case the light bulb flickers and the flow of electricity is impeded by the short in the line. This is the effect of venial sin -- we still have a connection to God but it is damaged and the flow of grace is on and off.

But, if we cut the electric line completely there is no flow of electricity to the light bulb at all. The light is dead. This is the effect of mortal sin -- our connection to God is severed completely; we lost sanctifying grace totally and thus are spiritually dead.

With that background, now to your question. We begin with understanding of how we are saved. John 3:5-6 --

Jesus answered, "I tell you the truth, no one can enter the kingdom of God unless he is born of water and the Spirit. Flesh gives birth to flesh, but the Spirit gives birth to spirit."

Jesus is saying here that to be saved, that is, to get to heaven, we must be "born again". That happens when we are baptized. Baptism is not only a sign of the New Covenant and initiates a person into the Christian Faith (like circumcision is the sign of the Old Covenant and initiates the Jewish boy into the faith), but also indwells in us the Holy Spirit and Sanctifying Grace.

Thus, in the Sacrament of Baptism we are re-born in the waters of Baptism and born into the Spirit of God.

Baptism is a permanent mark on the soul. It can never be removed. Even if a person ends up in hell, he still has the mark of Baptism on his soul.

The Spirit, however, can be quenched by our venial sin (a short in the electrical wire) or lost by our mortal sin (the cutting of the electrical wire).

Jesus taught us that the Sacraments are administered by the Church, usually by the priest.

Thus, when we sin mortally we enter spiritual death and a new act of grace must be initiated. This new act is accomplished by the Sacrament of Confession. We had to come to the Church for sanctifying grace originally through the Church, thus when we lose that grace, we must come back to the Church, who is the administrator of sanctifying grace.

This is why Jesus delegated the power to forgive to his priests. Jesus, himself established the Sacrament of Confession in John 20:21-23

Again Jesus said, "Peace be with you! As the Father has sent me, I am sending you."  And with that he breathed on them and said, "Receive the Holy Spirit. If you forgive anyone his sins, they are forgiven; if you do not forgive them, they are not forgiven."

We know that this power to forgive or deny forgiven is a power of the priesthood because these verses also is the establishment of the Sacrament of Holy Orders. The "sending you" and "breathed on then and said, Receive the Holy Spirit" is ordination of a priest.

Thus, we have the Sacrament of Confession because Jesus personally commissioned it. What Jesus has establish we cannot ignore.

By the way, the reason a priest would deny forgiveness to someone is when they are not genuine in their confession. Confession requires repentance and contrition. If a person does not genuinely offer repentance and contrition then he cannot be forgiven in the Sacrament.

1a. Why do we have ‘mediator’s’ in the Catholic faith (ie. The Pope, Bishops, saints etc)?

Jesus is the ultimate mediator, but we all participate in mediation because we are family. The Bible teaches us that all Christians are part of the Body of Christ and part of the family of God. Thus, we are to pray for our brothers and sisters. Several verses who an intercessory prayer (1 Tim 2:1-7; Eph 1:22-23; 5:21-23; 6:18-19; Rev 5:8; Rom 12:5, 10; 15:30; Col 4:3; 1 Thess 5:25; 2 Thess 1:11; 3:1; Gal 6:2, 10). Intercessory prayer is also mentioned in the Old Testament -- Tobit 12:12.

We are all to be intercessors especially for our family members in the faith. The Saints in heaven are also included in this. They intercede for us. They, too, are part of the Body of Christ, the family of the faith. They are not dead, they are more alive than us. James 5:16 teaches us that the "The effectual fervent prayer of a righteous man availeth much." There are no greater righteous person than those in heaven and no one with more effectual prayer.

All these petitions, from all sources, rise up to Jesus, the ultimate mediator.

The Pope and Bishops are leaders of the Church and the priest their assistants  (Acts 20:28; 14:22; Titus 1:5). God has always had a Magisterial authority. Jesus appointed Simon Peter as the first Pope of the New Testament and established the "Chair of Peter" to which would sit the successors of Peter. Before that Moses and his successors upon the Chair of Moses, which Jesus mentioned in Matthew 23:2, were the authority. Moses was, therefore, a Pope (which just means "Father"). Abraham was a Pope (father).

Upon each of the five covenants leading up to the New Covenant with Jesus, there was a "Chair" of authority in which sat a Pope (father and leader of God's people).

2. Why does the Catholic Church have so many protocols, structures, rules and regulations?

The Catholic Church does not have a lot of protocols, structures, rules, and regulations. The basic rule of the Catholic Church is the Ten Commandments and the two Great Commandments to love given to us by Jesus. The rest is about explaining those Commandments. People always look for loopholes to justify their sin, so the Church writes official explanations to make it clear what sin is and is not, and how to live a good Christian life.

The structure of the Church was modeled after the Romans, who has the most effective organizational structure known to man. The idea of the "corporation" of today is modeled from the Catholic Church. In order to administer a global Church their has to be an effective organizational structure.

But, as for many regulations, the Catholic Church has few. The Law of the Old Testament has 1000's of regulations. Jesus put away all those regulations and chastise the Jewish Leaders, such as the Pharisees for placing burdens of regulations upon the people.

Islam has 100s of times more regulations than the Catholic Church.

3. Was there a hierarchy of sorts in the early Church as there is today? Did our Lord intend for the Church to be hierarchical? Did our Lord establish a hierarchy?

Yes, as already mentioned, the book of Acts records the early organizational design of the Church, and Jesus himself established a hierarchy with the Papacy as the head. God has always had structure for his people (as Genesis says, God is not a God of chaos). God has always commissioned a hierarchy (such as the Chair of Moses, Abraham and the Patriarchs).

This is the way God wants it.

We know for a fact that the Popes in the first century had hierarchical authority over the whole Church. Pope Clement I, in around A.D. 86, issued orders for the Corinthian Church to get their act together. Since Pope Clement was not the Bishop of Corinth, the only way he could have had the authority to command the Church of Corinth is to be Pope of the Church.

Also St. Ignatius, in A.D. 107, reminds the local churches to remain in obedience to the Bishops.

4. Explain the Holy Trinity. Where is the Trinity referred to in the Old Testament?

The Jews do not have a concept of the Trinity, but the Old Testament does allude to the Trinity in Genesis, for example:Genesis 1:26 we read, "...let us make man in our image." There are many other references that allude to Trinity (see the Catholic Encyclopedia article link at the bottom of this post. Scroll down in that article to the subtitle, "Old Testament").

From the article The Trinity, from Catholic Answers, we read:

The doctrine of the Trinity is encapsulated in Matthew 28:19, where Jesus instructs the apostles: "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit."

The parallelism of the Father, the Son, and the Spirit is not unique to Matthew’s Gospel, but appears elsewhere in the New Testament (e.g., 2 Cor. 13:14, Heb. 9:14), as well as in the writings of the earliest Christians, who clearly understood them in the sense that we do today—that the Father, the Son, and the Spirit are three divine persons who are one divine being (God).

Also at Catholic Answers see the articles, God in Three Persons and the Divinity of Christ.

For a whole list of verses indicating Trinity, see Scripture Catholic articles, Jesus Christ's Divinity and The Holy Spirit and Messianic Prophecies Fulfilled by Jesus Christ.

You may also be interested in this debate between Dave Armstrong of Biblical Evidence for Catholicism with Muslim apologist Shabir Ally: Reply to a Muslim Apologist Concerning the Two Natures of Christ and Trinitarianism (vs. Shabir Ally)

As for a definition of Trinity, the Trinity is a mystery; we cannot completely understand the reality of God as Trinity. The definition from the Modern Catholic Dictionary is:

A term used since A.D. 200 to denote the central doctrine of the Christian religion. God, who is one and unique in his infinite substance or nature, is three really distinct persons, the Father, Son, and Holy Spirit. The one and only God Is the Father, the Son, and the Holy Spirit. Yet God the Father is not God the Son, but generates the Son eternally, as the Son is eternally begotten. The Holy Spirit is neither the Father nor the Son, but a distinct person having his divine nature from the Father and the Son by eternal procession. The three divine persons are co-equal, co-eternal, and consubstantial and deserve co-equal glory and adoration.

Also see the article on the Holy Trinity from the Catholic Encyclopedia.

I hope all this helps to understand Catholic teaching on these subjects.

God Bless,
Bro. Ignatius Mary