The “host” becomes the Body of Christ when the priest says the words, “This is My Body” during the Mass. The wine becomes the Blood of Christ when the priest says the words “This is My Blood.” Until that point, it is simply bread (of a sort) and wine.
Therefore, if somebody took unconsecrated hosts and wine from a Catholic Church, it would simply be theft, not blasphemy or desecration of sacred things. We don’t want to be wasteful or anything, but until the consecration, it’s just ordinary stuff.
Your question is perfectly reasonable and not in the least offensive.
During the Eucharistic Prayer, during Mass, the bread and wine are consecrated, and by the power of the Holy Spirit through the action of the priest, the bread and wine cease to exist and become the Body and Blood of Christ, under the appearance of bread and wine.
As long as the elements of the Eucharist remain recognizable in their appearances, the Real Presence of the Body and Blood of Christ remain.
Hope that helps.
sitetest
I certainly don’t take offense at the question. Yes, the bread only becomes the body of Christ during the consecration of the mass. There is a point during the liturgy wherein the priest holds up the Eucharist, and a bell is rung to signal the transsubstantiation. (Contrary to canon law, many parishes omit the bell for insubstantial reasons, but the bell only signals the transubstantiation; it is not a necessary part of it.) (Just as “transformation” refers to a change of the form, “transubstantiation” refers to a change of the substance.)
Within the tabernacle, there are often hosts which have already been transubstantiated. These may be stored for “Eucharistic services.” These services are prayer services with many aspects of a mass, but because they are conducted in the absence of a priest, there can be no transubstantiation; therefore, hosts which are already transubstantiated are used. Such hosts may also be used to be brought to those who are sick and could not attend mass, or for Eucharistic adoration, when they are exposed, but placed under vigilant watch.
During Mass, during the Eucharistic prayer, as the celebrant repeats the words of Christ at the Last Supper.
The question you asked is completely inoffensive.