A Jew's task in this world is to do the will of Hashem. This raises the practical question whether smoking is consistent with Hashem's will. I believe it can be demonstrated without a doubt that smoking is against Hashem's will. This is true whether or not smoking is technically forbidden. It also remains true even if a specific argument against smoking is flawed. The collective weight of all the arguments together provide certainty that Hashem does not want Jews to smoke.
1. Smoking may be forbidden by the Torah
A number of poskim consider smoking forbidden, in fact an isur deoraisa. Not all poskim agree, but there is good reason to avoid a behavior that could well be an isur deoraisa, violated thousands of times by a habitual smoker.
2. Smoking damages health
Even if we suppose that damaging one's health is technically permitted, it is obvious that health is better than its opposite. Therefore smoking is a bad thing.
3. Smoking may be a violation of Yom Tov
Smokers believe they may smoke on Yom Tov since they light from a pre-existing flame. However this permission only applies for commonly accepted pleasures. Smoking is no longer common in society as previously. For this reason smoking on Yom Tov has become questionable at best.
4. Smoking is a waste of money
A smoking habit can cost thousands of dollars a year, and many times more than that over a lifetime. Think how many yeshivos and shuls could be supported with that money. Consider how many poor families and poor brides could be provided for with all the dollars Jewish smokers have "donated" to cigarette companies.
5. Smoking is a taaveh
All the sifrei musar teach us to control our taavos in order to achieve kedusha. Smoking is a habit forming taaveh which reinforces our physical inclinations It is therefore spiritually detrimental for a Jew to smoke.
6. Smoking is detrimental to relationships bein adam lechaveiro
Smoking is harmful to other people through second hand smoke. In addition most people find cigarette smoke unpleasant. We are supposed to practice chesed towards other people, and smoking can be antithetical to chesed.
7. Smoking destroys opportunities for mitzvos
Many smokers die early from smoking. Think about the lost opportunity to learn Torah and do thousands of mitzvos because of dying years before one's time. Think of the grief of family and and the years taken away from being a loving grandfather, father and husband.
8. Smoking dishonors Hashem's name
For good reasons smoking is looked down upon in today's society. When a Jew smokes it sends a message that he lacks self-control and does not care about his welfare.
Some smokers justify their habit because tzadikim in the past smoked. But we have medical knowledge that was unavailable to previous generations, and it is pretentious to assume tzadikim smoked with the same kavanos as today's smokers. This rationalization of the yetzer harah does nothing to reverse the damage caused by smoking. Anyone who is honest will admit smoking is against Hashem's will.
