Liturgy is the due worship of God through the celebration of the mystery of Christ and cannot be understood without Faith for though it is a duty, it is one of love and worship. It is the duty of baptised Catholics to participate in this worship for it is one of thanks giving and gratitude of the salvation which Christ brings to all humanity. Participation in the liturgy gives the laity zeal and strength to be witnesses of the Faith. To do this we can look to the Church for guidance and the Church points us in the direction of these various liturgies. Liturgies should not to be taken lightly or put to one side when life seems too busy. All are called to participate in the various liturgies which allow us to worship of God in all aspects of our lives and builds us up to be a Temple of the Lord strengthening us to teach the message of Christ.

It is the duty of Baptised laity to know what is going on during the liturgy, particularly the Mass, in order to give the fullest worship to God and also to help us our service of telling others. One must actively join in the liturgy, not necessarily by having a specific job but through prayers, witness and maintaining a correct disposition of person. This allows the lay participation to be fruitful because it is fulfilled with knowledge and understanding which leads to it being active . The laity must be open to receive this gift of grace as it is God's gift and not man's work with which one can participate in the liturgy.

When taking the vocation of priesthood the soul is conformed to God through the Sacrament of Holy Orders. Therefore the priest is acting as the person of Christ, at the altar during Mass, when speaking the words at the homily, when guiding the laity through the liturgical year and when absolving sins or bestowing sacraments which give the laity the graces they need to fulfill their own vocations. This means that priests must “zealously” encourage active participation of the laity in the liturgy.

Though the liturgy is fulfilled in the celebration of the paschal sacrifice this does not necessarily mean that all liturgies take place in the Mass. The sacraments which celebrate the glorious mysteries of God, for example, do not need to be celebrated within the Mass but they are liturgies because the follow a particular rite, they have the congregation of lay faithful attending and are carried out by an ordained minister. Similarly in areas where there are few priests the lay faithful may participate in liturgies of the word, because they are worshipping God by focusing on the paschal sacrifice as directed by a particular rite. The congregation are guided by an Ordained member of Religious or commissioned lay person.

Liturgical Art is an example of the liturgy, the paschal sacrifice of Christ is portrayed in the context of rite, congregation and ordained ministry for the worship of God. It is often used to keep the focus of participants at a meeting, those attending mass or even in the family home during the private prayer of the domestic Church.

Liturgical architecture is also important to acknowledge, though seen more so in older buildings where Churches face East facing the rising sun which is a symbol of the risen Christ. The altar placed in the sanctuary, emphasising the holiness of the sacrament; the placing of the lectern, altar and chair highlighting the Sacred Word of God, the Paschal sacrifice on the altar and the priest, the person of Christ. The baptismal font placed near the entrance of the Church symbolising the sacrament of baptism the first initiation into the Church leading to the mystery on the altar. All these and many other symbols in the liturgical architecture of church's help with the participants understanding and closeness to God.

The liturgy is naturally centered around the Holy Trinity as God brings His plan to fulfillment. The mystery of the Trinity is made present by liturgical action so that our lives may be joined to it. When one participates in the Mass one acknowledges and adores God the Father and listens to His Word, takes Christ into himself at communion and becomes a temple for the Holy Spirit who prepares us to accept Him during the liturgical celebration offered by the whole Mystical Body of Christ both head and members.

God is love and because the liturgy is centered around the Holy Trinity the sacrificial nature of perfect love is revealed to us in the perfect sacrifice of love on the altar.

The liturgy is a time when the lay faithful come to worship God, who communicates to them through the action of the priest. The liturgy is an opportunity to prepare ones self for the perfect liturgy in heaven for as St Iraeneus states “The Glory of God is the living man, but the life of man is the vision of God”. When we participate in the Mass we are joining with the liturgy in heaven. The earthly liturgy takes place under a 'veil' of signs and is a foretaste of the heavenly liturgy which we are on a pilgrimage to in heavenly Jerusalem.

In both the heavenly and earthly mass it is the same celebrant, Jesus, who presides during the mass, though on earth he does this through His priests He is also present in the sacrifice on the altar. We are reminded of this in the preface during Mass.

As part of their vocation members of the priesthood and religious orders take part in the Liturgy of Hours or the Divine Office. The beauty of this Liturgy is that every hour of the day somewhere in the world this “celebration of the mystery of Christ” is taking place and there is a constant prayer being offered up for the universal Church. Though it is the duty of the religious to say the Divine Office as part of their vocation many lay people also join in this prayer of the Church. It is the duty of Catholics to pray for the world in which they live, for their children and to fulfill this service they too join their prayers to that of the universal Church, “all who render this service are not only fulfilling a duty of the Church, but also are sharing in the greatest honour of Christ's spouse”.

The liturgy of the year, commonly know as the liturgical year, enables the faithful to follow the major aspects of Christ's active ministry. This is reflected through the readings at Mass which over a three yearly cycle cover about 70% of Sacred Scripture and are placed into several seasons.

40.8% New Testament read on Sunday's and Major Feasts

71.5% New Testament read on Weekday's

3.7% Old Testament read on Sunday's and Majot Feasts

13.5% Old Testament read on Weekday's

NB this excludes psalms

The Liturgy of the Year can be explained with a diagram:

The main seasons of the year are:

Advent, a time of eager preparation and anticipation. Advent lasts for four Sundays.

Christmas, a time of feasting and celebration for the birth of God our Salvation and Redemption. This season ends on the feast of the presentation of the Lord in the Temple.

Lent, forty days of repentant preparation, this time for the death of Christ, the completion and fulfilment of our Salvation.

Easter, forty days of feasting for we truly have been saved. Easter ends on the Feast of Pentecost, the birth of the Church.

Ordinary time, this does not mean boring time but a time outside of the major seasons of feasting and fasting. This is when one looks at the various teachings of Christ during His ministry and these are the periods between the major seasons.

There are also Marian Feast Days, Pentecost, Feasts of various Saints scattered amongst these.

It is important for Catholics to partake in the full liturgical year and is in itself a useful tool for parent to help teach their children the whole mystery of Christ. The liturgy of the year can naturally be followed by participating in weekly mass but also within the family home one may have a picnic for the birth of John the Baptist on mid-summers day, bake angel cakes for the feast of the guardian angels or a torchlight procession for all souls. The liturgical year can therefore be used for the service of evangelisation which all baptised Catholics are called to by being a witness to work colleges, society friends and all those one comes into contact with as celebrations of the appropriate season should “suit the conditions of modern times”. It is through the various feasts within the year the spiritual and physical formation of the faithful can be complete, for it is through the re-reading and re-living of the most significant events in salvation history that we are able to live our lives in Christ.

To live the fullest life in Christ it is also important to build a personal prayer life outside of the Mass, to help one grow closer to God. One way which the Baptised faithful can do this as part of the institution of the wider Church is through the Divine office, the Liturgy of hours.

The liturgy reaches it's fulfillment during the Mass. It is within the Mass that the Paschal Sacrifice truly takes place and Christ is actually present. The priest and congregation are present with the intention to worship God. Because the liturgy is the worship of God and celebration of the Paschal Sacrifice it can only be understood through Faith. St Paul reminds us of the requirement of faith for understanding and how this can be achieved through the liturgy. "How then are they to call upon him in whom they have not yet believed? But how are they to believe him whom they have not heard? And how are they to hear if no one preaches? And how are men to preach unless they be sent?".

The Baptised faithful gather together for liturgy during the Mass. The congregation and priest have their own specific roles clarified in the rite of the Mass. At the celebration of the Paschal Sacrifice the priest offers the offerings to God on behalf of the laity. It is through his vocation that his soul is conformed to God and Christ can work through him to speak words of guidance in the homily and bestow the graces of Christ on His people by calling to the Holy Spirit to come down and change the offerings of Bread and Wine into Christ's Body and Blood to nurture all baptised faithful and help them to “become perfect like your Father in heaven”.

In the Mass the laity listen to the Word of God, it is through Sacred Scripture that we come to know Him, that we are guided by Him, that we are refreshed and healed by Him. It is part of that witness of faith that Catholics are called to pass on the Good News by reflecting the Word of God through daily living or through discussion, but we ourselves must have an understanding of what it is God is asking of us.

The climax of the Mass, "through which the work of our redemption is accomplished," is the liturgy of the Eucharist. Baptised Catholics share in the adopted sonship of Christ through their baptism when they share in His death and resurrection. It is the duty of Catholics to share in the preparation of the last supper, the death and resurrection of Christ which is an actualisation during the liturgy of the Eucharist. By taking Christ into us He is able to use us to reach everyone we come into contact with, it is important for Catholics to fully participate in this great mystery to be of service to the public around them in the worship of God.

“The liturgy is the celebration of the mystery of Christ and in particular his paschal mystery. Through the exercise of the priestly office of Jesus Christ the liturgy manifests in signs and brings about the sanctification of humankind. The public worship which is due to God is offered by the Mystical Body of Christ, that is but his head and by it's members”

As we can see in the quote from the compendium above there are three important elements which are required for liturgy to take place, these shown in the diagram below:

The Congregation are the lay faithful who are attending the event or liturgy.

The Ordained Ministry are those who have taken the vocation of Holy Orders and Priests or those of Religious Orders (note: some religious orders have lay members - see the comment by Ludolphus below).

The Rite is the way the Church instructs how the celebration should be carried out. For example, there are rites of the celebration of the Mass, rites for the celebration of the Sacraments but there are also rites for liturgies outside the Mass.

It is interesting to note that there are four main types of rite Roman, Antiochian (Syria), Alexandrian (Egypt) and Byzantine. It is from these four that over 20 different rites have derived.

Update: Thanks to Ludolphus and Joseph Shaw for the comments below. I do appreciate criticism when it helps make things more accurate.