I certainly agree that you have an unalienable right to an opinion and to express it at any time or by any means at your disposal. Only a statist like, say, John McCain or Van Jones would disagree.
But you are not entitled to your own facts. Progressives used the exact argument you advance to obtain passage of Amendment XVIII in 1919. Alcohol-related crime increased with its prohibition.
Lots of people have advanced arguments about regulating fatty foods, transfats, and soft drinks due to adverse health effects. You can pretty safely bet that national dietary regulation will appear in the next few years. (But I am sure you wouldn't because some people have gambling problems.) The rationale is the same as yours: some people can't help themselves, so they need a nanny government.
WRT religion, there are a lot of people in high places who think that all, or at least some, religions are destructive to social order and individual mental health. There are innumerable examples in history. Nero banned Christianity, Pope Leo X excommunicated Luther, later Popes launched the Inquisitions, Calvin burned Michael Servitus at the stake, Salem had their witch trials, and the 20th century was far, far worse for people of faith. In each case, the political elites believed that they were acting positively to achieve some noble objective such as maintaining social order, preserving the salvation of individual souls, or preserving the Faith and the Church. In the incomparably evil cases of the 20th century, idealists who aspired to create a new socialist man or an ubermensche severely persecuted adherents of particular faiths. The Hitlers and Lenins of the world strongly believed Judaism and Christianity to be subversive of their ideas on social order and ridiculous, superstitious impediments to individual potential. To them the argument against allowing the continued existence of these faiths was just as persuasive as your argument against marijuana.
Psst ... I really don't care if you're a religious-right conservative, either. We probably agree on a lot of the important stuff. BTW, it was the Progressive Party that advocated Prohibition. I am way farther from the progressives than you, my friend.