That’s a good question and it deserves a good answer.
“And the LORD said unto Cain, Where is Abel thy brother? And he said, I know not: am I my brother’s keeper?” (Genesis 4:9)
I detect “tone” in Cain’s answer to God. Simply put, Cain was as much as saying, “How should I know? It’s not my job to watch him.”
But the truth of the matter is: “No one lives to himself and no man dies to himself.” (Romans 14:7)
If we read beyond that verse and look at it in the context in which it is written we will see Paul telling the Romans never to be a stumbling block to their “brother”. That is a pretty clear indication that we Christians have a responsibility to others, to those who share our faith and those who do not.
For example, if I say I am a Christian that means I should be living in a manner that is pleasing to God. If I live in a way that displeases God, partaking of the things of the world, even in one area of my life, a non-believer could easily be deceived into thinking that the way I am living must be acceptable to the Christian faith. He could assume that God is much more tolerant of sin than He really is. A non-believer could easily have an “if it’s okay for her as a Christian than it must be okay for me” understanding.
If I display mental carelessness, selfishness, moral insensitivity, spiritual weakness, or sin of any kind, everyone who comes in contact with me will suffer. My example may cause others to stumble. You may ask, “How can you possibly live up to that high standard?” 2 Corinthians 3:5 tells me that “our sufficiency is from God, and Him alone”.
Also, if I as a Christian see a brother or sister of the faith straying off the straight and narrow path that leads to heaven, and walking instead on the broad road that leads to hell, it is most certainly my responsibility to approach him or her in an attitude of mercy, grace, and love, and help him or her to get righted on the narrow path once again. He or she may or may not listen but that is out of my control. But, if God should ask me, like he asked Cain, “where is your brother” I will be able to reply, “he was on the broad road to hell, Lord, but I went to him and showed him his error. I explained to him what will happen if he doesn’t turn from his wicked ways and return to you.” I will have a clean conscience.
John the Baptist came before Jesus with a loud message, “REPENT”. Multitudes were walking that broad road that leads to destruction. The Baptist was born for this very reason: “to be his brother’s keeper”, to tell the world that they were walking in sin and to help them get on the path of righteousness.
You may be the only bible that some people will ever read.
If you are a Christian, are you a good example to others? You may be the only bible that some people will ever read. What is your manner of living saying?
What would your answer be If God should ask you? Would you be able to give a reply that would please Him? Or would you answer like Cain did, “How should I know”?