According to the Catechism the “Sunday Eucharist is the foundation and confirmation of all Christian practice. For this reason the faithful are obliged to participate in the Eucharist on days of obligation, unless excused for a
serious reason (for example, illness, the care of infants) or dispensed by their own pastor. Those who deliberately fail in this obligation commit a grave sin (2181).
Those who ”obstinately persist
in manifest grave sin are not to be admitted to Communion” (Canon 915).
Therefore, if teachers persistently fail in their Sunday obligation they are not to receive Holy Communion. To receive communion
unworthily is a form of sacrilege. It would be committing another grievous sin in addition to the mortal sin. If a teacher thinks there are serious reasons preventing him/her from fulfilling their Sunday obligation they should call their parish priest so they
may organise the regular reception of the Sacraments.
Take note of the teaching on the matter of sacrilege:
To respond to this invitation we must prepare ourselves for so great and so holy a moment. St. Paul
urges us to examine our conscience: "Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the body and blood of the Lord. Let a man examine himself, and so eat of the bread and drink of the cup.
For any one who eats and drinks without discerning the body eats and drinks judgment upon himself." Anyone conscious of a grave sin must receive the sacrament of reconciliation before coming to Communion