Should the denial of the Eucharist be applied to those that support greed? What about all the other sins? Can and should I be denied the Eucharist if I still haven't forgiven my neighbor for killing that tree in my yard? Where is the line drawn and who determines when the Eucharist can be received and when it cannot?
That's why confession is absolutely required (in the Orthodox Church at least, and technically in the Catholic as well) before one receives communion (every time!), although I know for a fact that even the Orthodox have become lax on that issue. By confessing and repenting of your sins, the priest knows that you can receive the Eucharist because your sins have now been forgiven.
Remember, repentance does not mean you say you are sorry and then go back to doing what you did before...it means change of mind (metanoia). You basically reject your wicked ways and promise to God and yourself never to do it again! Obviously, someone who continues to publicly support abortion publicly states that he or she doe snot repent of that sin, and that he or she is not on the same sheet of music as the Church is. As such he or she has no business asking for a Catholic Eucharist!
As for private sins you mention, that is on your conscience! If you line up to receive the Eucharist and you have not confessed and repented of your sins you do so at your own risk. Please, don't let me stop you! The priest cannot assume that you have not confessed or repented and in some cases the priest has no clue who you are or if you are even a member of the Church! So, he offers you the Eucharist in ignorance and in good faith...but the burden is on you.
And even if you do confess before communion, but do not confess all your sins, then all your sins are presumably not forgiven because God would know the truth and while you are fooling the priest and yourself, you cannot possibly hope to fool God, if you believe in him. So you are really digging your own hole.
And if you think that you have not sinned since your last confession, and that you don't need to confess, then you don't need the Eucharist any more than Jesus needs one! You are perfect, so why bother.
If you publicly support or profess any particular sin, the Church should deny you communion. A Catholic cannot be a Catholic in good standing and publicly support abortion any more than publicly support contraception or advocate divorce or premarital or extramarital sex. Yet, we know that Catholics engage in premarital and extramarital sex, support same-sex "marriage," are practicing homosexuals and lesbians, use contraceptives, support abortion and believe in divorce privately.
They may very well never go for a confession but regularly receive the Eucharist, and there is nothing an individual priest can do about it if he doesn't know what they believe, do or say in private. Once their beliefs and practices become a public domain, the priest has a duty to deny communion lest it count against his conscience.
The Church determines when it can be received and when not, and the Church, speaking through the bishops, has said it cannot be received by these people.
There’s no such thing as the “sin of supporting greed,” by which I assume you mean capitalism. Many other sins - for example, feeling angry at a neighbor who cut down a tree in your yard - are probably venial sins, or if they are mortal sins, can be forgiven with repentance and in confession.
Abortion is murder and is not in the same league as the other two things at all. Publicly supporting this mortal sin is encouraging others to commit a mortal sin, and making it a part of public policy is doing so to the nth degree. These people should not go to Communion but many of them have persisted in doing so anyway. Obviously, now it’s time for a stronger, more public approach to what is - on the part of a public official - a public sin and one that is much more serious because of his public responsibilities.
You sound like you’ve read too many “personally opposed” Catholic pols and maybe a touch too much of the anti-capitalist - er, excuse me - anti-greed screed of the Catholic left.