The Church defines what a third order (secular order) is as follows:
Associations whose members lead an apostolic life and strive for Christian perfection while living in the world and who share the spirit of some religious institute under the higher direction of that same institute are called third orders or some other appropriate name” (CIC 303).
It is a very succinct definition but one that is very rich in substance. Let us look at the different aspects of the definition.
The first thing to note is the use of the term association. Secular Third Orders are “associations”. Associations are basically groups of Christians who join together for some common purpose or way of life. Associations can take various forms and can have various purposes. Some are “public” like third orders and some are private. They can be directed to a particular work, a particular devotion, to Christian perfection or to several purposes at once.
The definition continues by stating that the members of the association lead an apostolic life (vita apostolica). While every Christian is called to be an ‘apostle’ by baptism and to live an active Christian life, the tertiary embraces a particular way of living an apostolic life. They live this life both as a Christian and according to the spirituality and charism of the Order they belong to. Introducing others to Christ in evangelization, feeding the poor, catechesis etc, are all aspects of living an apostolic life. They very much commit one to live in this way as a life not simply as part of say a prayer group or club.
Jesus called all his disciples to “be perfect”. All are called to this Christian perfection, all are called to be holy. One of the purposes of third orders is to “strive for Christian Perfection”. The tertiary vocation is a calling to a particular way of following Christ. It is a vocation that commits the tertiary to “strive” by the grace of God for Christian perfection, to seek to more and more to “put on Christ” as St. Paul put it in his letters (i.e. Gal 3:27). Being a member of a third order provides ways to do this and help from ones brothers and sisters. One commits oneself to ‘conversion of life’ as a disciple of Christ and as a tertiary.
In the World
This next aspect is also of great importance. For the tertiary is not called to live the life of a religious but rather is called to be a Christian in the world. A tertiary is called to live his ‘secular character’ and while he may draw certain things from the traditions of the Order and its spirituality that other Christians would not embrace normally --the tertiary is by his very call from God a lay person in the midst of the world. Let me quote from the document from Pope John Paul II on the Vocation of the Lay Faithful, speaking of the “Secular Character” of the layperson he writes:
“…the lay faithful “live in the world, that is, in every one of the secular professions and occupations. They live in the ordinary circumstances of family and social life, from which the very fabric of their existence is woven”. They are persons who live an ordinary life in the world: they study, they work, they form relationships as friends, professionals, members of society, cultures, etc. However, the Council considers their condition not simply an external and environmental framework, but as a reality destined to find in Jesus Christ the fullness of its meaning…The lay faithful, in fact, “are called by God so that they, led by the spirit of the Gospel, might contribute to the sanctification of the world, as from within like leaven, by fulfilling their own particular duties. Thus, especially in this way of life, resplendent in faith, hope and charity they manifest Christ to others… The lay faithful’s position in the Church, then, comes to be fundamentally defined by their newness in Christian life and distinguished by their secular character.”(CF 15).
Spirit of a Religious Institute
This would refer to the sharing of the charism and spirituality of the order by the tertiary. Tertiaries share authentically in a secular manner in the spirit of the religious institute they belong to. The secular dimension of the charism forms part of who they are in the Church and in the world and guides their apostolic works.
Under the Higher Direction of that Same Institute
Tertiaries though they are ‘autonomous’, are under the higher authority of the Order they are associated with or part of. For instance they have often some of the same superiors as do the religious of the institute i.e the Provincial, and the General. This authority is regarding only the things that involve their lives as tertiaries, and is one of the great means towards holiness.