We have 2000 years of historical precedent that establishes Christianity as a religion. There are churches of various Christian denominations all over the world and hundreds of millions of people identify as Christians.
A personal relationship with Christ is an important part of Christianity, but is is simply not reasonable to state that a religion with hundreds of millions of followers is not a religion.
The definition of religion is "the belief in and worship of a superhuman controlling power, especially a personal God or gods." Therefore, Christianity is a religion. Although, as a Follower of Jesus myself, I understand that it goes beyond a religion into a relationship of sorts. It's a different relationship from any other but Christianity could still be described as such.
I'm going to go out on a limb and define Christianity as one's relationship with the maker of the Heavens and the Earth. Why call it religion? I don't like that word because I feel that word encompasses all the different denominations that exist and the growing number of people who are turned away by each faith that says, "We do it better." I don't want to be a part of that trend.
Jesus said to go forth and make disciples of all nations; not denominations. It's like we took something that was simple and made it more complex, which is in our human nature so I'm sure God saw it coming. He's probably up there chuckling and saying, "Bless their hearts."
As a christian, I believe in Jesus. I love Him. I trust Him. I will do my best to follow Him wherever He leads. I am not going to say that I'm religious because that puts me in that category of feuding faiths over who's right and who's not.
Also, I don't wish to be a part of that group that says, repent or you will burn in Hell. That's not something I feel is our job to do. Jesus didn't do that. He spoke mostly in parables and offered himself. He didn't demand, and he didn't push. That's why I don't like that word religion, and I don't think that Christianity is a religion. Christianity is the acceptance of Christ in your life and a representation of your relationship with Him.