So far as I know, many countries have strict laws to regulate smokers not to "share" their smoke in many ways so I do not consider we should restrain their freedom of smoking in some places that would not cause any problem, but certainly passive smoking is meant to be pretty hurtful to vulnerable group of people like pregnant women or children if it is not ruled in a proper manner.
Despite companies/factories which causes air pollution are built in industrial areas, the air can spread everywhere without question and the amount of pollution is much much more than smokers' contamination. Even in a big country with broad soil like America, the US government has had strict legislation and harsh enforcement to regulate industrial pollution since they understand how damaging the industrial pollution will lead to the population and the environment, which is in a way irreversible.
"As we all know the problems caused due to the so called RELIGIONS. Do you guys think this should be banned?"
Something is a problem only if it hurts someone/something else than yourself.
When someone prays for his/her family, where's the problem ?
When someone smokes alone in his/her apartment, where's the problem ?
When someone wants to shoot a bullet in his/her own face, where's the problem ?
The liberty is to do whatever you want respectfully of each others. If your question is "Should we be against the liberty of someone because I do not share his opinions ?" Do not forget we are 7.5 billion peoples on this earth and we are all different.
I am a smoker, and I am smart enough to not be smoking when children, pregnant women, old persons, or just non-smokers are around me. I enjoy my liberty without forgetting the liberty to not smoke of someone else.