Ethically, there are two issues: the first is intoxication. In this case, marijuana is comparable to drinking alcohol. If it's wrong to get drunk, it's wrong to get high.
Secondly, it's illegal in essentially all countries (but tolerated in some places, like Amsterdam). The Bible says that it is wrong to break laws except, of course, if the law is trying to compel us to sin. For example, if the law takes away the right of pharmacists or nurses to refuse to participate in abortions ("conscience clause"), then it is still wrong to participate in abortions. Shadrach, Meshach, and Abednego went into the furnace rather than worship the king as a god. So it is okay to break the law to follow the higher Law of God. It is not okay to break the law just because you want to, you need a very good reason to appeal to a Higher Law, and you have to be prepared to face the consequences.
On a personal note, I do drink (good beer, some nice hard alcohol like nice whiskey/scotch) and I do occasionally smoke tobacco (only good tobacco like hookah, pipe or cigar) and marijuana. I used to smoke quite a bit of pot but I've pretty much stopped. If someone's passing the pipe to me, it's hard to not... But I haven't bought any for myself in a couple years so that was my compromise to get myself off of it -- I'd smoke it if I was offered, but wouldn't buy it. Now, I think I've mostly grown out of it. I've done some other drugs in my day but I've never been really addicted to anything, I think it's different if you get addicted.
Some people say it's wrong to use any kind of recreational substances, including alcohol or tobacco. I think it's
better to avoid them, certainly, but I believe moderation is okay (drunkenness, especially habitual, is condemned in the Bible).
But smoking marijuana is breaking the law and that's not okay. But so are downloading music and movies and jaywalking. Indeed, when Seattle passed a resolution to put marijuana possession at the bottom of the police priority list (since they couldn't legalize it, this was toleration), the police had to make up for the money they weren't getting by ticketing people for marijuana possession by enforcing the laws against jaywalking instead and ticketing those people.
So
how wrong smoking marijuana is, I think, depends on the law in your area and your cultural standards (not just your buddies, but the whole community). But since you have had a problem with it in the past and you seem to have a connection between becoming a Christian and stopping smoking pot, I think it's best just to try to stay sober.
1Th 5:5-8 said:
For all you are the children of light and children of the day: we are not of the night nor of darkness. Therefore, let us not sleep, as others do: but let us watch, and be sober. For they that sleep, sleep in the night; and they that are drunk, are drunk in the night. But let us, who are of the day, be sober, having on the breast plate of faith and charity and, for a helmet, the hope of salvation.
Men who go into battle do not go into battle drunk or high or they will die. Our life is a battle against the devil. We need to be alert to protect ourselves from temptations to sin. If I get drunk in a situation like a club, there can be many sexual temptations and I may act on them whereas I wouldn't do those things sober. Sometimes I've had attacks from devils when I'm drunk because I've let my guard down. It's a very real war out there, that's why it's best to be prepared and avoid substances.
