I think the whole sin thing is misunderstood. We have fleshly desires, we are made of flesh. We lust after people, we overeat, we over drink, etc. Whenever one of these things becomes more important than your own life, then that would be an addiction. Like sex- it is natural to want to have sex, it is built into us, we needed to fill up the earth. If there was no sex, then there would be no people. But if you want to have sex and you don't care about getting STDs, AIDS, etc, and the sex becomes so important that you are willing forgo all the dangers- then that would be an addiction.
We can't be free of these things, but we who have God are able to work on our spiritual self- the part which is in a union with God. And if someone doesn't believe in a spirit, then they wouldn't see the benefit. I wouldn't expect them to.