The fifth precept as given by the Catechism of the Catholic Church, paragraph 2043 is “You shall help to provide for the needs of the Church.” The same paragraph further explains that this precept “means that the faithful are obliged to assist with the material needs of the Church, each according to his own ability.”
This fifth precept places us back within the topic of “stewardship.” As was covered earlier in treating the seventh commandment (“You shall not steal”), all that God created is given for a universal purpose such that while individual persons do have a right to private ownership of property and goods, all external (material) goods are to be used as stewards, minding that God provides for all. Mindful then that all that we have and are comes to us as gifts from God, proper stewardship includes the right and just use of property both for our own needs and for the needs of others, beginning with those in our own home and extending to others in our Church and in the local community. Therefore, each person is called to make use of and freely give of their material wealth that they themselves have first received in such a way that no one will be lacking – as we are stewards of that which comes from and properly belongs to God who made us. By such stewardship, we are acting in accord with the two great commandments: loving God by giving in return from what He Himself has initially given; and loving neighbor by offering of ourselves for the benefit of others.
Given this perspective on stewardship, this precept acknowledges that just as every person has material needs, so too the Church has material needs of its own which must be met for the Church to carry out her life and mission of offering the gift of salvation in Jesus Christ. As the Church exists for the sake of our eternal good, carrying out her works in the world, the state of the Church dwelling within the world requires that her material needs in the world need to be rightly met – which is most properly accomplished when the members of the Church themselves provide for such material need. For the Church is not meant to nor should she ever need to conduct business as though she were a retailer of goods or a service industry that sells her work for profit. Properly it is by way of we members ourselves, each with resources of our own to offer, that the Church is to be built up and sustained in her life and mission to the world so that all her legitimate material needs will be met (including such needs as giving just wages to those who labor in the Church on behalf of the eternal good of all her members, in providing and maintaining buildings within which the Church dwells, and in fulfilling the material needs of the Church for carrying out the saving works of Christ on behalf of all people). Were there no material support of the Church by the faithful, the works of salvation would be less effectively carried out and would likely not remain readily available to the people to partake of and to receive.
Thus, as members of the Church all of us are called to be part of providing for these material needs. Just as the precept acknowledges that each is to provide according to their ability, it is fitting that each person take seriously the call to stewardship – and to regularly and prayerfully seek God’s guidance in being good stewards so as to rightly give back to God what he first gave to us and to also offer of ourselves for the eternal good of others as a way of loving God and neighbor toward the salvation of all souls in Jesus Christ.
For further reading: In the Catechism of the Catholic Church, paragraphs 2041 - 2043 gives the brief definition and the official formulations of the five precepts. Likewise, paragraphs 2402-2405 remind us of basic principles of stewardship.