I'm sick of Christians saying Christianity's not a religion. Only Protestant Christians do this. Catholics and Orthodox don't. Here's why Protestants say it:
1. They want to distance themselves from formal liturgical churches. I like formal liturgical churches so this doesn't hold water with me.
2. They want to agree with people who bash religion. I don't know any anti-religious people who joined Christianity because it's "not a religion". Most secular people get pissed off when Christians say Christianity is not a religion.
3. They want to set themselves apart from the bad things done in the name of religion. In reality they sound like they're shrugging off any blame for the sins of the past. Like it or not, some Christians did evil things.
4. They want to be "cool" and "edgy" and "shocking". They fail. Saying Christianity is a religion is way more shocking than saying it's not.
5. They want to emphasize that it's about a relationship with Jesus. Which it is. I don't see how this conflicts with Christianity being a religion. It makes Christianity a distinctive religion but it doesn't make it any less of a religion.
The web site adherents.com has two interesting things on this here and here. The first link says other religions do this. I can believe this. A lot of Buddhists claim they're a philosophy, not a religion. But every Muslim I've met uses the word religion. The second link quotes James 1:27: "Religion that is pure and undefiled before God, the Father, is this: to visit orphans and widows in their affliction, and to keep oneself unstained from the world." (ESV) This is from the Bible. It doesn't say "relationship", it says "religion".
While everyone else boasts they're not part of a religion, I claim it with pride. It's honest. I don't claim everything done in the name of religion is good. Members of my religion did horrible things thinking it pleased God. But members of my religion also did great things thinking it pleased God. I believe organized religion has brought more good into the world than evil. I only wish I was a better follower of Jesus. If you read my blog you know I'm not.
P. S. Most secular people bash "organized religion" instead of any specific one. They always mean the group they grew up in.