Over the last year or so I've been thinking a lot about what it means to be a member of the Body of Christ. I'm certain that if I thought of nothing else for the rest of my life I would never cover it all, but I'll just share my thoughts a little at a time.
Colossians 1:18 tells us that Christ "is the Head of the body, the Church." We enter the Church through the Sacrament of Baptism, therefore through Baptism we become members of the Body of Christ. We find a very detailed description of this Body in 1Corinthians 12:12-26, comparing each of us to a foot, an ear, and so on. Verse 26 concludes that each member should treat all the other members equally, and that when one member suffers, all suffer, and when one is honored, all rejoice.
If we stop to think about this we will hopefully, through the Grace of God, gain some understanding of how this correlates to sin. Sin is "failure in genuine love for God and neighbor", "an utterance, a deed, or a desire contrary to the eternal law" and it "wounds the nature of man and injures human solidarity." (See the Catechism of the Catholic Church, paragraph 1849.)
When one person sins, the entire human race is affected. Because sin distances us from God, each of us is that much farther away from Him because of the sins of everyone else, and therefore, everyone else is farther away from Him because of OUR sins.
~Becca