As with anything concerning sin, there is no strict commandment that covers this issue about whether or not you should be taking mind altering substances. However, there is only one "way" use of wine or marijuana is actually permitted. This is the way jesus used it, and any other person that wants a greater connection to your soul. If you are using it with the idea that it is a sacriment towards your god. As an aid to purify and silence your inner mind. If you meditate on the silence and stillness.

So, if you have the stillness of the mind under control, then wine and marijuana would not be altering your mind. Or if you have a really active mind, and these substances aid you in relaxing your thoughts, then it should be considered a mind alteration for the better.

If you are using these substances while thinking sinful thoughts, or committing sins, then, of course, it is definately also a sin.