If You Don't Know It's Wrong Is It Still A Sin?

Sorry about the long absence.  I babysit one of my grandsons on Mondays and this week we went and spent the day at Lake Michigan.  Then yesterday I wasn't feeling well.  Not sure if it was a cold or allergies but I just couldn't function.  Doing much better today. 

Now on to God's word.  I ran across this verse today.  The way it is worded raises an interesting question. 

James 4:17(NKJV)

17Therefore, to him who knows to do good and does not do it, to him it is sin.

According to this Scripture, to not do something that you know you should do is a sin.

So does it follow that to do something wrong if you don't know it is wrong, isn't a sin?  In other words, is the sin not so much in the deed but in the knowing that the deed is wrong? 

Interesting.  I'm going by memory here and I don't have Scripture to back it up but it seems to me that I read somewhere that a similar situation applies to those who have never heard of Jesus.  Something to the effect that if someone has never heard the good news of Jesus and has never been given a chance to accept Him, they will not be held accountable for not accepting Jesus. 
 

I can see the similarity in the two policies.  Interesting.  Something for further study.