I think many people start smoking before they are really able to make wise decision, it's usually to show off, peer pressure ect. I tried one as a teenager but hated it -and felt no pressure to conform.
All four of my children have smoked, my ex husband and his family were all smokers. They all came to dislike it as different stages of adult life.
Some smoked because they were addicted, some because it helped them cope.
My daughter and youngest son read a book by ' Alan Carr ' On giving up - it worked instantly with my daughter ( I believe it helps you to understand the mental addiction to smoking ) She has never smoked again. My youngest , it failed the first time because he had been told to give up because of health issues ( he was only 18years old ) it wasn't his choice, so the book didn't work. However when he was ready to make the decision himself, the book help and he quit smoking. My eldest gave up about five years ago. My middle son smokes tobacco from time to time.
I don't think it is a sin, but I equally don't think it is wise- but I find that many you claim the moral high road with drink and smoking often eat many things that are unwise. In the western world we have a lot of food products that equally damage our bodies - I have yet to hear a sermon of ' diet '!!
When we become Christians we are not instantly transformed in to perfect people- coming to faith is when the process of change begins. God deals with the things In our lives in different ways, and at different times.........
Rita