United We Stand
You shall reprove your fellow and do not bear a sin because of him. (Lev. 19:17)
Dan was on a luxury ocean liner when he heard banging in the cabin next to his. He entered the cabin and saw a man banging on the floor. He asked him, "What in the world are you doing?" The person replied, "I am making a hole in my side of the boat." Dan gasped, "You are what?! He replied, "I am making a hole. I paid for this cabin and I can do what I want over here. It is none of your business." Dan replied, "Listen, we are all on this boat together; if you go down we are all going down! What you do is very pertinent to me!"
When the Torah mentions the commandment to rebuke a fellow Jew it ends with the words, "And do not bear a sin because of him." The Targum translates, "And do not receive a punishment for his sin." The Targum is teaching us that all Jewish people are unified. If a Jew sins and you could have prevented it, then you get punished for it. My actions affect you, and your actions affect me - we are one unit. For a Jew to say, "What I do is my business and doesn't affect anyone else," is categorically false. It is as if I have co-signed on your loan. If you default on your payments, the bank will come after me. I didn't borrow the money - but I am responsible.
The Chofetz Chaim writes that when we die God may say to us "Why didn't you keep Shabbos, learn Torah, and recite blessings?" You're going to reply, "Me?! I observed all those mitzvot?!" But because every Jew is a guarantor for every other Jew, you bear another's sin if you did not try to correct him. Each of us is obligated to reach out to others and bring them closer to the Creator.