Q. 1. Does the Catholic Church teach anything about people receiving Communion while in a state of sin, such as those living common-law?
A. 1. In the Holy Bible, we read,
"Therefore whoever eats the bread or drinks the cup of the Lord in an unworthy manner, shall be guilty of the body and the blood of the Lord." [1 Cor. 11:27]
Regarding this Bible verse, the Catholic Church teaches that Catholics must receive the Holy Eucharist in a state of grace. Catholics must go to Confession prior to receiving Holy Communion if they are in a state of mortal sin. For it is serious to consume the Holy Eucharist without believing that it is truly the Body (the Real Presence) of Jesus. To do so is a desecration.
In 1 Corinthian 11:27, Paul says that eating or drinking in an unworthy manner is equivalent to profaning (literally, murdering) the Body and Blood of the Lord. If the Eucharist was but a symbol, as the Protestant believe, one could not be guilty of actually profaning (murdering) Jesus in the Sacrament of the Holy Eucharist. We cannot murder a symbol. But here, in this verse, Saint Paul, the divinely inspired apostle of God, makes it clear that when you receive Communion in an unworthy manner, you are profaning the Body and Blood of Christ. Such a behaviour is total disrespect for the Sacred Person of Christ.
In the same Chapter of 1 Corinthians, Paul continues by saying, ""For all who eat and drink without discerning the body, eat and drink judgment against tehmselves. For this reason many of you are weak and ill, and some have died." [1 Cor. 11:29-30] In other words, those who receive the Sacrament of the Holy Eucharist in an unworthy manner, in a state of mortal sin, they can expect to be punished by God by illness or death.