1 Corinthians 8 : 7 Howbeit there is not in every man that knowledge: for some with conscience of the idol unto this hour eat it as a thing offered unto an idol; and their conscience being weak is defiled.  8 But meat commendeth us not to God: for neither, if we eat, are we the better; neither, if we eat not, are we the worse. 9 But take heed lest by any means this liberty of yours become a stumbling block to them that are weak.

This first verse shows us two sides of the proverbial coin. If some is eating something offered to an idol, and knows it was, but does it anyway is committing a sin because it goes against their conscience. Now for those who regard the idol as nothing can eat the same thing would not be sinning because they did not regard the idol as anything and be eating it with a clear conscience. Next we see that the meat is really not the issue. If we do anything without a clear conscience is probably going to be a sin.  Anytime we feel in our heart that we are doing something we should not as a christian then it is a sin. As Christians our conscience, the Holy Ghost, alerts us when we are about to do something we should not and we should not do it. Then we see if what we are doing is going to cause someone to sin we should not do it because they could be weaker in their belief and sin. This could cover a lot of subjects, way too many to mention here, and so we should be aware of the weakness of younger believers in Christ.  Sometimes the only example of Christian living that a person has is the one people see us live.