Picture this family scenario: It is time for dinner. The family gathers around the table, gives thanks in prayer, and then eats a meal that Mom prepared. Now imagine that there is no communication between any of the family members. Further add that when they are done with the meal, most of the members each goes his own way and does not have any further interaction with the others. Finally, add in the fact that this is what happens at every single meal that the family has together. Could we truly say that they are "together" or would it be better to say that they are just coincidentally in the same place? Much of the spiritual and emotional health of a family is determined by their level of interaction (or lack thereof). This is recognized by more than just those in the Church.
If the Catholic parish is supposed to be a spiritual family (think about it: it has the Blessed Virgin as "Mother", a Priest as "father" and the laity are the "brethren"), then we need to learn something from the illustration above. As I spoke about in last Sunday's homily, coming together in unity is not optional for Catholics. We are supposed to be supporting one another. No, that does not mean that every Catholic is absolutely required to be at every event the parish has and spend time with every single other parishioner who is present. Yet, if the opposite is true (someone never spends time with others in the parish) then something is not healthy. Maybe someone needs to overcome some socialization issues (most do in some way), but that presumes that he or she is working on it.
Yes, the Church requires Mass attendance, but not fellowship afterwards; true. Remember though, the requirement from the Precepts of the Church are the "bare minimum"! It also only requires the laity receive Communion once a year. Interesting to note, most Catholics today receive Communion every time they go to Mass (even when they are in a state of sin) but rarely reach out to their brethren in fellowship. Somewhat backwards; right? We should never seek to be "bare minimum" Catholics.
This is why I call it "Community of Communion". We are already a community (by nature of the fact that we come together), but we have to take the extra step for it to be properly "communion". This is why the Church has always said that someone who breaks fellowship cannot come to the Sacrament of Communion. If we are out of communion personally (through any unrepentant sin) then it is a radical contradiction to partake of Communion when we are in a state of sin. This is the point St. Paul makes more than once in the Scriptures, and we must take it to heart.