Paul continues his narrative on whether or not we, as Christians, are free to eat meat sacrificed to idols.  The point he is making is that when we exercise our liberty in Christ Jesus, we need to be sure that others are not offended or misled by watching us.  Though we have the knowledge that we have liberty because Jesus Christ died to set us free from the law and from sin, others do not have that knowledge.  They are accustomed to not eating meat sacrificed to idols because that is what the law has taught them. Just as some of the disciples still taught that you had to be circumcised because they did not yet have the understanding of their freedom in Christ. We, being the stronger, should then give up our freedom to do certain things.  Not because the action itself is a sin, but because it causes our brother or sister to stumble and we have sinned against them. Any sin against anyone is a sin against Christ. So we should use our knowledge, spoken in love, to edify our brothers and sisters and not to harm them.