The 7 Sacraments of the Roman Catholic Church explained.

List of common questions: (leave a comment if there is something you wish to add).

What are the 7 Sacraments?

Are the Sacraments (as a whole) needed for salvation?

Why do we do them?

(Note i had to remove color from the text, so please ignore my comments in regards to that).

The 7 Sacraments are a group of 7 sacred ceremonies which allow us to experience God's saving presence. To use Cannon Law to explain them, we reference the Catechism. 

Cannon Law 1210

Christ instituted the sacraments of the new law. There are seven: Baptism, Confirmation (or Chrismation), the Eucharist, Penance, the Anointing of the Sick, Holy Orders, and Matrimony. The seven sacraments touch all the stages and all the important moments of Christian life: they give birth and increase, healing and mission to the Christian's life of faith. There is thus a certain resemblance between the stages of natural life and the stages of the spiritual life.

Cannon Law 1211

Following this analogy, the first chapter will expound the three sacraments of Christian initiation; the second, the sacraments of healing; and the third, the sacraments at the service of communion and the mission of the faithful. This order, while not the only one possible, does allow one to see that the sacraments form an organic whole in which each particular sacrament has its own vital place. In this organic whole, the Eucharist occupies a unique place as the "Sacrament of sacraments": "all the other sacraments are ordered to it as to their end."

So, to break it down for you,

These are Sacraments of Christian initiation. Baptism, Conformation, and Eucharist (First Holy Communion is given a special tidal for being the first time we meet the Body and Blood of our Lord).

These are Sacraments of healing. Penance (going to confession) and Anointing of the Sick (often called Last Rites).

These are Sacraments at the service of communion of the mission of the faithful. Holy Orders, (For example, the Priesthood) and Matrimony.



Why do we celebrate them?

To answer, Baptism, the Holy Eucharist are both, needed for salvation, the exception to this can be found in Lumen Gentium Here 13-19 

(Evidence is in red, with important parts in darker red, if you know the passage, skip below the red to save time)

Jesus answered, "Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God."
-John 3:5 

"I am the living bread which came down from heaven; if anyone eats of this bread, he will live forever;and the bread which I shall give for the life of the world is my flesh. The Jews then disputed among themselves, saying, "How can this man give us his flesh to eat?" So Jesus said to them, "Truly, truly, I say to you, unless you eat the flesh of the Son of man and drink his blood, you have no life in you; he who eats my flesh and drinks my blood has eternal life, and I will raise him up at the last day. For my flesh is food indeed, and my blood is drink indeed. He who eats my flesh and drinks my blood abides in me, and I in him. As the living Father sent me, and I live because of the Father, so he who eats me will live because of me. This is the bread which came down from heaven, not such as the fathers ate and died; he who eats this bread will live forever."

-John 6:51-58

*Note: Read John 6:66 Jesus is willing to lose followers over this message, and he does not explain it, as if it were a parable, he mean it literally.

Conformation, not everyone knows as much about this one. Suffice it to say, one passage from the bible clears it up greatly.

"Now when the apostles at Jerusalem heard that Samaria had received the word of God, they sent to them Peter and John, who came down and prayed for them that they might receive the Holy Spirit; for it had not yet fallen on any of them, but they had only been baptized in the name of the Lord Jesus. Then they laid their hands on them and they received the Holy Spirit." 

-Acts of the Apostles 8:14-17

As you can see, from the "only" Baptism is just the start of the life of a Christian. 

*Note: We hold it replaces the Old Testament Circumcision, and it therefore appropriate around the time of Birth. 

Penance 

On the evening of that first day of the week, when the disciples were together, with the doors locked for fear of the Jewish leaders, Jesus came and stood among them and said, “Peace be with you!” After he said this, he showed them his hands and side. The disciples were overjoyed when they saw the Lord.
 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’s sins, their sins are forgiven; if you do not forgive them, they are not forgiven.”
-John 20: 19-23

*Note: First few Verses are for context.


Here, Jesus gives the Priesthood he has formed the power to forgive sins....Through the power of God. This is very important, they do not forgive sins on their own, only God has that power, Websites such as Here Which states

"Only God can forgive sins, and Christ, being God, has the power to do so as well, but He never communicated any such power to His disciples, nor did they ever assume any such power to themselves. The key to understanding the meaning of John 20:23 lies in the previous two verses: “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.’” He sent them, as He is sending us, to bring the good news of the way to salvation and heaven to the whole world. Jesus was leaving the earth physically but promised God would be with them in the person of the Holy Spirit living in them. As they proclaimed the gospel, they could honestly tell people who believed in that message that their sins were forgiven, and they could honestly tell people that did not believe in the message that their sins were not forgiven and that they stand condemned in God’s eyes. Jesus said, “Whoever believes in the Son has eternal life, but whoever rejects the Son will not see life, for God’s wrath remains on him” (John 3:36). "

"Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but only he who does the will of my Father who is in heaven."
-Matthew 7:21

The Fact is, they could, and they did do what this website claims they did not. And it does mean a Priest can forgive sins, as he has been delegated the authority to do this, he does not do it out of his own power, that would be a terrible Heresy, and the Church would be the First to condemn anyone who says they can do that, save of course the second coming of Christ.

Anointing of the Sick

It is seen often in the bible

"Is any among you sick? Let him call for the presbyters of the Church, and let them pray over him, anointing him with oil in the name of the Lord; and the prayer of faith will save the sick man, and the Lord will raise him up; and if he has committed sins, he will be forgiven." 

-James 5:14       


What this is in effect, is a last chance to bless the dieing person, forgive their sins, and give them peace of mind that they enter into their fathers house. Its Biblical, and practical on both a spiritual, and physiological realm. 

Matrimony

He answered, "Have you not read that he who made them from the beginning made them male and female,  and said, `For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh'?  So they are no longer two but one flesh. What therefore God has joined together, let not man put asunder."

-Matthew 19:4-6 

I don't think anything else is needed.


Holy Orders  

The Idea of Holy Orders is really, that of a Priesthood who like the Jewish counterparts in the days of old (Pre-Rabbinic Judaism) Offered sacrifice, forgave sins (Delegated to them by God as in *Leviticus 4:20) and remained Celibate for their time office (I need to provide biblical evidence, i am aware, since it does not directly say this, see below in Blue)*"And do with this bull just as he did with the bull for the sin offering. In this way the priest will make atonement for them, and they will be forgiven."
I had Issues before over the meaning of the word "Atonement" so Here is the definition "Reconciliation or an instance of reconciliation between God and humans."

"It [Show bread] belongs to Aaron and his sons, who are to eat it in a holy place, because it is a most holy part of their regular share of the offerings made to the LORD by fire."

Leviticus 24:9

1) Only Priests are Suppose to eat Show bread.  

"But the priest answered David, “I don’t have any ordinary bread on hand; however, there is some consecrated bread here—provided the men have kept themselves from women.”

 -1 Samuel 21:4

David replied, “Indeed women have been kept from us, as usual whenever I set out. The men’s bodies are holy even on missions that are not holy. How much more so today!”  So the priest gave him the consecrated bread, since there was no bread there except the bread of the Presence that had been removed from before the Lord and replaced by hot bread on the day it was taken away. 

-1 Samuel 21:5-6

2) Only Celibate men are allowed to eat the Show bread.

The Jews of the time, served at the temple for only a short time, during which they were celibate, until they returned home, then they could, assuming they were married, participate in the marital act. Here is a Wiki-Page which confirms what i say, but its not a great source, there is a footnote in 3 of my bibles making reference to this fact.

3) Priest only remained celibate while serving as a Priest

From these 3 things, we have the end result on "Why Catholic Priests Don't Marry". They serve for life, or until they leave the Priesthood.  --  Its worth noting Catholic Priests in the Middle ages and before sometimes married, and sometimes were ordained for only limited amounts of time, this is a Discipline, (subject to change as needed) not a infallibly defined truth.