In my opinion, religions can be many things. Marx, I believe, said that religions give consolation to people, so that they can bear with the oppression they suffer. This is close to what you said, that it is a kind of drug. However, it can be much more than that. It can become intellectual tool for governance. Islam is a religion which is used as a means of power. It homogenise people, by eliminating opposition, and subordinate the rest to the religious leadership, this is exactly what ISIL does and Mohammed did. So religions are ideologies. The problem with religions is that as ideologies they become tools for tyranny. Even without interference with politics religions are still awful because they cripple people intellectually preventing them from contributing positively to the betterment of the world.