Why Some Holy Days Are Moved to Sunday

Its important to remember that, historically, holy days were generally the same as holidays. A holy day of obligation meant that there was no work that day. It was a day of rest and prayer. Mass attendance was but one part of what was expected on those days.

Catholic holy days have their root in Jewish holy days, when all temporal activity was expected to cease. The entire day was dedicated to God, not just an hour of worship.

In modern times this expectation still exists in canon law:

Can. 1247 On Sundays and other holy days of obligation, the faithful are obliged to participate in the Mass. Moreover, they are to abstain from those works and affairs which hinder the worship to be rendered to God, the joy proper to the Lord’s day, or the suitable relaxation of mind and body.

Fitting Mass attendance into one’s work day is not the spirit of the holy days of obligation. In today’s world, outside of a few exceptions, it’s simply not the case that the faithful can abstain from work during the week. The Church moves such holy days to Sundays as a way of not building up unnecessary burdens upon the faithful (Matt 23:4).

In some parts of the country (and the world) there is also the practical problem of having enough priests to cover Masses at all the churches on those days.