"Religion is the opiate of the masses". That's what Karl Marx said. And you know what? I agree with him. I cannot be sure what he meant by the comment, but I am pretty sure that our reasoning is quite different, at least I hope so. Let me explain why I think he's right.
First, let me clarify that I am only speaking of the Christian religion, since that is the only one that I can speak to from experience. By "religion" I mean the outward rituals, traditions, behaviours that are associated with a religion. So, for Christians that would mean going to church, tithing, taking communion, helping others etc. Someone who does all the right things outwardly is considered a "good" Christian. I am not necessarily disputing whether they are good Christians or not. However, spirituality is something deeper that is not manifested outwardly in such an obvious manner. And at the end of the day, I think it is spirituality that really matters; what is going on inside, and in your relationships; how you are relating to others and to God. That's where the opiate part comes in.
Merriam-Webster says that an opiate is, "something that induces rest or inaction". So, I think that, unfortunately, there are a lot of Christians whose religion, actually induces rest or inaction. In other words, they do all the right things and think that they are "good". They give their money and their time to the church and they don't even stop to think where their heart is. They think that the outward manifestions of their religion keep them safe and right with God. I think they are wrong and that's why religion serves as an opiate. Its a false security that let's them think that they can live how they please as long as they keep up religious appearances. They don't have to actually love their neighbours, or forgive others, or swallow their pride, or any of those harder things that are required in order to be spiritual. So, they rest contentedly in their bubble of religious behaviour and never aspire to change, or grow, or learn. After all, they have already "made it"; they are "good".
Anyway, that's what I think. So, I agree, begrudgingly, with Karl Marx, the communist atheist.