I agree that a major point to make to Christians that the prohibition is causing more harm than good, and it is more important to point out that it is theologically wrong to attempt prohibition (or ANY type of coercion, inhibition or oppression) in the first place, regardless of the outcome. Many Christians believe that the ends justify the means, but God calls us to have our means justify our ends. Does God want people getting high? There is theological evidence to thoroughly back that he probably does not, but, regardless of this, God doesn't call for coercion of his laws. God does want to see people being faithful toward him, but, just because one is not sinning by tangible action, does not mean that one isn't sinning in one's own heart. Faith requires to believe in one's own heart as well as act faithfully with one's actions. One may not commit adultery with one's physical body, but, if one looks onto another with lust, then one has committed adultery in one's own heart. What's more is that, once one stops watching, the people who commit adultery in their hearts will go out and do it tangibly. It is just as bad before or after stopping them from committing it, and it was wrong to try in the first place. Virtue cannot be coerced. It must be chosen. God has clearly laid out what ends he wants us to accomplish in this world, but, more importantly, is that we do it the way God calls us to accomplish these ends. We must show others that we are Christians by our love, not by oppression.
That's the message we need to be sending out.
