Yes, there are guidelines for this sort of thing. The Orthodox have similar views, from what I gather. Since the Eucharist is viewed as the true Body and Blood of Christ, it is considered sacrilege among Catholics and the Orthodox for a person in a state of serious sin to receive communion. (The Anglicans also recognize the Real Presence but tend to practice open communion, allowing anyone to take it, whereas the Catholic and Orthodox hold you must be baptized/confirmed and in a state of grace). But it is not permitted to simply refuse to give the Sacraments to someone. There are guidelines for this.I'm not very familiar with nuances of Catholic teachings, but decisions like denying someone Communion are often up to higher-ups in the Church, aren't they? The average member doesn't have the authority to determine who gets to attend Communion inside their church.
And I'm only speaking for myself. My posts contain no "juvenile insults" or demonization of the Church as a whole. If you believe otherwise, feel free to point out where I said anything in this thread that qualifies as such.
"Canon 915, one of the canons in the 1983 Code of Canon Law of the Latin Church of the Catholic Church, forbids the administration of Holy Communion to those upon whom the penalty of excommunication or interdict has been imposed or declared or who obstinately persist in manifest grave sin:
Those who have been excommunicated or interdicted after the imposition or declaration of the penalty and others obstinately persevering in manifest grave sin are not to be admitted to holy communion.
The corresponding canon in the Code of Canons of the Eastern Churches, which binds members of the Eastern Catholic Churches, reads, "The publicly unworthy are to be kept from the reception of the Divine Eucharist"."
Canon 915 - Wikipedia