Communion with the Trinity is something that develops within a person. Not because of God but because the believer progresses in the virtues:
36. Invisible communion, though by its nature always growing, presupposes the life of grace, by which we become “partakers of the divine nature” (2 Pet 1:4), and the practice of the virtues of faith, hope and love. Only in this way do we have true communion with the Father, the Son and the Holy Spirit. Nor is faith sufficient; we must persevere in sanctifying grace and love, remaining within the Church “bodily” as well as “in our heart”; (Cf. Lumen Gentium 14.) what is required, in the words of Saint Paul, is “faith working through love” (Gal 5:6).
One must join the two: an outward stance within the Body of Christ as well as a growing interior life in God.
The second paragraph of this section reminds that sin damages our interior union, even if our exterior standing remains seemingly intact:
Keeping these invisible bonds intact is a specific moral duty incumbent upon Christians who wish to participate fully in the Eucharist by receiving the body and blood of Christ. The Apostle Paul appeals to this duty when he warns: “Let a man examine himself, and so eat of the bread and drink of the cup” (1 Cor 11:28). Saint John Chrysostom, with his stirring eloquence, exhorted the faithful: “I too raise my voice, I beseech, beg and implore that no one draw near to this sacred table with a sullied and corrupt conscience. Such an act, in fact, can never be called ‘communion’, not even were we to touch the Lord’s body a thousand times over, but ‘condemnation’, ‘torment’ and ‘increase of punishment’”. (Homiliae in Isaiam,6, 3: PG 56, 139.)
Along these same lines, the Catechism of the Catholic Church rightly stipulates that “anyone conscious of a grave sin must receive the sacrament of Reconciliation before coming to communion”. (CCC 1385; cf. Code of Canon Law 916; Code of Canons of the Eastern Churches 711.) I therefore desire to reaffirm that in the Church there remains in force, now and in the future, the rule by which the Council of Trent gave concrete expression to the Apostle Paul’s stern warning when it affirmed that, in order to receive the Eucharist in a worthy manner, “one must first confess one’s sins, when one is aware of mortal sin”. (Address to the Members of the Sacred Apostolic Penitentiary and the Penitentiaries of the Patriarchal Basilicas of Rome (30 January 1981): AAS 73 (1981), 203. Cf. Ecumenical Council of Trent, Sess. XIII, Decretum de ss. Eucharistia, Chapter 7 and Canon 11: DS 1647, 1661.)
It is not unknown among the sainted spiritual guides of history for the Eucharist to be encouraged as an aid to someone in serious sin. The danger in an absolutist approach is that the Eucharist becomes a “reward” for good behavior. Or for avoiding bad behavior.
Tangled up in this “worthiness” are matters outside of the moral realm. Some believers are asked to withdraw from Communion not because of serious sin but because of their juridical status in the organization.
Granted: serious sin and a public injury to the Body are two very important matters not to be taken lightly. My own sense is that one’s confessor is probably a better judge than the blanket application of Saint Paul’s caution–whatever he might have had in mind for the particular community of Corinth.
That said, in ordinary practice, a believer has no excuse for not seeking a deeper union with God through the practice of holiness and allowing the Holy Spirit to lead one into a more profound relationship with God. In fact, I would be concerned if I were in a situation in which serious sin were not present and I wasn’t growing in the virtues. The reception of Communion in that instance would indeed be more of a membership card than an expression of a desired communion or a means of spiritual nourishment to spur me forward. But again, this is where spiritual direction is essential.