As Christians, we are to exercise self-control (it IS one of the fruits of the Spirit, after all). When one is intoxicated (be it from wine, beer, liquor, pot, 'shrooms, whatever), the individual no longer has control. To willfully place one's self in such a condition goes against the very character of Christianity.
As to gambling, games of chance are, in and of themselves, harmless. But it is when the intentions behind the game move into lust and greed that sin enters the picture. Even a game of tiddlywinks can be sinful if the motive behind it is sinful (the game itself is not the sin, but the intent of the heart is the sin).
Just my personal opinion and conviction. Take it for what it's worth.
In Christ,
Trotter