Yes, it is a drug like many others, it is true that it comes from nature, like many others.
The bad part of drugs is that they create addiction, everything that creates the "need to have" is considered a drug.
Some are less harmfull than others, but they are not healthy any ways. In the case of Marijuana it contains THC which is a the same natural chemical that is produced by the hippocampus in our brain, but in a very small quantity, the quantity that our Creator considered necessary for us to function correctly (think, memorize, and learn correctly) . If we consume THC in a regular basis, our brain will start not producing it, so the need of it will begin and there it will start the "roll": need, consume, need consume and so on until not only the brain will be compromised but also the lungs, the PH and the sickness will show off and it will be no way back to the original health. On the other side it will harm the social relation with the family and true friends that are prosperous and live a healthy life.
I suggest all of you to stay away from it and any other drugs!