Let's suppose you're left-handed and you're visiting some muslim country. There in a restaurant, people start looking at you bad just because you eat with the left-hand, which is impure. So you ask why people are staring at you like this, and the concept of the-left-hand-is-impure is introduced to you. Eventually you finish your meal with the right hand, but that's very difficult and lots of food go on the table, on your clothes, on the floor.Originally posted by TWTCommish
As for the first: if that's ALL we do, then you're right, but introducing the concept of sin to some people who have not heard of such a concept is obviously a good thing.
How would you behave when you're back in your country ? Of course you'd go back to eating with the left hand, since it's how you've always done.
So, you'd be a sinner, 24 hours a day. After all, the Quran is the word of God too.