Really???? If I had said "Who is a Christian" many would just say "Me". The same with "What is Christianity", sensible answers would be it is a creed followed by a vast number of people. End of discussion.
But thank you for your pedagogic perusal.
Now, what is a Christian? What does a person have to do to be a Christian? Is being a Christian like being an Australian, Canadian or Greek, for example? Is being a Christian just a name or is it a way of life?
There you go, tear those questions apart!!!!!
I don't think the answer is quite as complicated as you're trying to make it, and you are trying to figure it out completely on your own and "on paper". First thing I'll do is answer the original question based one my understanding up to this point.
What is a Christian? A Christian is a person who has been reconciled to God through Jesus work on the cross. It is a very real, personal, and supernatural act (event) that fills us with His Spirit as we were created to be. It takes the missing aspect of what we need to be complete and makes us whole. This is not something one of us can answer for you, this is something only God can give you any kind of certainty on. We can sit here and debate all day long on the number of denominations, the age of the earth, or why a God would allow the world to be so bad if He's so powerful, but ultimately only God can convince you. The good thing is you are asking the right question, and in my opinion one that is not asked nearly enough even in church houses.
I was not raised a Christian, nor was I convinced to join by some smooth talking preacher. I also didn't come to truth by seeking it out and asking questions like you are now. God pulled me in and opened my eyes to truth through the hardest trial of my life, honestly the only kind of thing that could snap me out of the mental prison and chains this world puts us in through sin. I didn't believe in the bible, nor was I in anyway interested in learning about it. Even after a couple years of calling myself a Christian (before my incident I liked the "idea" of Jesus and joined the social club and philosophy I thought Christianity was) I had no interest at all in actually learning anything about it. I was very much a "Christian by name" as you asked here. I understand how you see it like that, I know because that's the way we are raised from birth to see the world from every outlet.
The catch 22 with my description is that anyone can just chop my testimony up to "personal experiences" and write it off if they want to. The thing is that the people closest to me, the ones that saw me go through my motorcycle wreak that took the function from my right arm, the ones that were there and saw how that completely broke me. They saw me every day and saw my spirit crushed, they saw me with my head down, they heard me when I could talk about nothing else but how much I hated not having the use of my arm. They wanted to help but could do nothing, and I knew this was a problem I couldn't fix as well. I couldn't, science couldn't, heck even what I thought God was and my false view of Christianity couldn't, I was stuck in this cold, merciless, uncaring, and dead world stuck with no hope.
One of the most amazing things about my conversion, to me anyway, is at the time it happen I wasn't even sure I wanted to believe in God anymore, if I ever truly had anyway. I just knew I wanted to die, I couldn't help myself, and I had enough, that was it. I hit my knees one day, Sept.28, 2013, and didn't cry out to God or Jesus, all I said was "I can't do this anymore, I can't do this anymore, I can't do this anymore, World you win, I loss and I quit." That was it. The next day I woke up new (on Sept.29, 2013), it took me until lunch to realize I hadn't thought about killing myself all day. This was something that went through my head at least every five minutes everyday for 2 solid years, and I couldn't help it at all, I didn't want to think about this but had no control over the thoughts filling my head. I had no clue what happen, but I knew 2 things, first I knew it was from God, second I KNEW Jesus was His son. I'm not sure how to describe exactly how or why I knew these things, but I knew them. Now back to the people around me, they saw this too. They saw me go from my depressed, broken, self pitying state to having new LIFE , they saw the power of God and what it did to me. It honestly blew my mind, I dragged my jaw around for a couple months upon realizing "it's all real? It's all real!!"
I made this long enough and am more than willing to converse and/or answer question, anything like that, also there is a lot more detail and things that I left out, but that's the best way I could think to answer what a Christian is. Thanks for asking too.