I think religion and addiction are very similar, they have both become habitual routines that people follow, most of them don't quite know why and to understand it you need to take a step back.
They both have a set of beliefs that people unquestioningly accept:
"god exists: I need to drink"
"I will go to heaven: I am worthless"
People accept these things because they have been made to think like this, religion is force fed to us all our lives and it can be hard to turn away from it, I am a confirmed atheist and have been all my life but I still find myself making references to the bible or christiaity without realising it. For addicts, they're treated in certain ways that create certain feelings, or they engage in behaviour that creates or maintains feelings and it just becomes like second nature in the same way religion does.
Both religion and addiction are ways to cope with the World, we go to church and believe in god because we want to hope there is something better out there, or we need help with our situation, or we can hide behind it and pretend everything is ok. No-one is physically addicted to religion but I know peple who are psychologically addicted to it and their lives can be in the same state as substance abusers. Of course there are people who aren't addicted but there are also people who use drugs and alcohol and aren't addicted.