It is an interesting thought - one that I’ve questioned before but still am not sure of the answer.
From what I understand, if one leaves the Catholic Church and makes a profession of faith in another church, they would be excommunicated. At that point, they wouldn’t be able to receive the Eucharist in the Catholic Church.
However, if one moves from Catholicism specifically to Holy Orthodoxy, how does the Catholic Church view them after that move? I mean, an EO Christian can receive the Eucharist in a Catholic Church (according to the Catholic Church) if they are properly disposed to do so (ie, followed fasting rules, no mortal since, recent confession, etc.). Also, since EO sacraments are valid and licit, that would include EO Confession. Once that sacrament takes place in the EO Church then the sinner would be pardoned of all transgressions.
At that point, if a Catholic-turned-Orthodox Christian would receive Confession in an EO Church, wouldn’t that person then be forgiven of their sins and be able to receive Communion (from the Catholic Church’s view even in a Catholic Church)?
Do I have this right? If so, since they are allowed to receive Communion in a Catholic Church and had a recent confession, there would be no mortal sins any longer on the person’s soul.