I guess it depends on how one defines religion, KayElCee. And with so many definitions getting flung around, the argument can not really be settled as a whole. To me, it’s not religious, but I must admit it took me a long time of study and participation to come to that conclusion. I resented the frequent use of the word “God”, especially referring to “God” in the masculine pronoun. And frankly I think AA would be better if they were able to purge a lot of their present traditions that were handed down by various religions (including the excessive use of that “God” word). I think it’s foolish that so many groups use the “Lord’s Prayer” to close a meeting, as that has such a strong christian association.
But it comes down to the fact that AA is a voluntary, free, private, incredibly loosely organized association that accepts no outside contributions, and noone is (or should be) compelled to come, nor should it be compelled by anyone other than its own member, to change in any way.
I hate it when we have court-mandated folks show up, resentful and disruptive, and not ready to hear what we have to offer. I’m glad that there’s Rational Recovery and Secular Organization for Sobriety out there, to offer alternatives for other folks. I wish it were available to more.
But even the court-mandated folks have a choice. They weren’t “sentenced to AA” as I’ve heard so many say. They were told they could end up with a sentence with less or no jail/prison time if they participated in treatment programs and attendance at groups like AA, and they agreed to it. They could have said “no thanks”, done their time, and then gone on their way (usually to be back pretty quickly, in my experience). I’ve patients who have done just that.
Does AA have flaws? Of course. Do I wish it would take steps to more rapidly facilitate its moving ever more closely towards its spiritual principles and further away from various religiously-driven thinking? You betcha! Do a lot of AA members hinder motion in that direction? For sure!
But it’s still the best thing I’ve ever found to fill the void that was still there after I gave up alcohol and drugs well over 16 years ago. And if my going to a meeting a week for an hour and talking on a daily basis with real-life friends who also go to meetings translates into religiosity, then I was grossly misinformed as to what religiosity consists of. 
FTR, I was never a Calvinist. My dad broke away from them when he married my mom, a Methodist. I grew up surrounded by Calvinism but definitely not of it, and proclaimed my own agnosticism in junior high (but did so very quietly, and not to my Grandma Mercotan. It’d have killed her, probably only days or weeks after she would have killed me).
Well, most of that stuff I just typed doesn’t belong in a GQ thread, but I’m not going to enter into the GD one on the topic, as I doubt I’ll change any minds (I don’t think I did last time I entered such a fray), and I’m content with the fact that I don’t know what makes it work for me, but it sure is working, after everything else I tried failed disastrously with terrible consequences for not only me, but my loved ones too.
Ta!