My question: is it valid and is it licit for a priest to say Mass when entirely alone? (ie no server, just the priest, the rites and God) I know this is not encouraged and that it is always preferred to say Mass with a congregation. But what about the priest who wants to offer daily Mass (I am one of them) with an unusual ministry, and do not always have access to my parish church? Or when one travels through a Muslim country? I cannot find a straight answer on this one.
Yes, it is both valid and licit.
It is far better, strongly preferred, that a priest have someone else there, to serve and/or make responses.
The reasons for this are two-fold. First, every Mass is an act for the whole Church. It is good to have others there. Second, priests will do a better job of saying Mass when others are there. It is certainly easier with a server and someone to respond. However, never imagine that another person has to be there for validity of the Mass. Ten thousand lay people at a Mass contribute nothing to the priest’s ability to say Mass and consecrate the Eucharist validly.
Also, a priest is never really alone when saying Mass.
There is an old phrase, "Father said Mass alone today, in the company of all the choirs of angels."
The Church Militant is not the only dimension of the Church that counts.
The norms covering this state that priests should not say Mass alone "except for a just and reasonable cause" (GIRM 254). The fact that the priest wants to or needs to say Mass is considered a good enough reason to say Mass alone. If memory serves, this is clarified also in the Directory for Priests. If it is a choice between saying Mass alone or not saying Mass at all, the obvious choice is to say Mass.
The priest performs a magnificent work of mercy when he says Holy Mass for an intention, when he prays for the living and the dead.
If we really believe what the Church says about Holy Mass, how can we think for a second that the priest should not say Mass every day, alone or not? Save The Liturgy – Save The World, right? Priests are not obliged to say Mass every day… but…
I would add the caveat that just because the priest is alone, that doesn’t mean that he is not bound to follow the proper rubrics in which ever Missal he uses, and follow the calendar. Mass isn’t the priest’s private property. He must use vessels and vestments and do it reasonably and right. Also, he should be sure that he observes decorum as to where he celebrates Mass. This requires conviction and discipline.
Concentration camps will be another matter. We will deal with that as circumstances require.