When a priest celebrates Mass each day, he offers each Sacrifice of the Mass for a particular person or intention. By doing so special graces from God are applied upon that person or intention. The act of offering prayers for the dead at Mass goes back to AD 235. Canon Law also confirms this practice and states, “In accord with the approved practice of the Church, any priest celebrating, or concelebrating is permitted to receive an offering to apply the Mass for a specific intention” (Can. 945 §1).
Anyone may ask a priest to offer a Mass for several reasons. For example, Masses can be offered in thanksgiving, for the intentions of another person (such as on a birthday), or as is most common, for the repose of the soul of someone who has died, including a deceased non-Catholic. There is no canonical rule against having a Mass said for a deceased non-Catholic. As a matter of fact, the opposite is true; the Church’s Code of Canon Law says, “A priest is free to apply the Mass for anyone, living or dead” (Canon 901).
Canon Law also states, “The Christian faithful who give an offering to apply the Mass for their intention contribute to the good of the Church and by that offering share its concern to support its ministers and works” (945 §2). This refers to a longstanding practice in the Church of offering a specified amount of money to the Church for a particular intention offered by the priest. This is not the act of selling something sacred for money (simony), but it is for the purpose of supplying items for Mass and for the support of the priest. In Dioceses of the United States, the standard offering for a Mass stipend is $10.
There are now two ways to request a Mass intention:
The intention for which a Mass is offered is always valid, whether or not the name is announced. This is the great grace of the Holy Eucharist, whose “spiritual value of a single Mass is infinite.” Canon Law does not oblige the mention of names at Mass. The Holy Mass is celebrated for the benefit of the person for whom the Mass is intended. That benefit is never lost, even if the name is not spoken.