What is a christian? Please Respond!

The Christian Experiment...

With recently re-entering the workforce I personally challenged myself not to share my beliefs or my faith with anyone at my job. I do this with the purpose that I'm hoping people will see a difference based on my work performance and attitude. I want to be a light (or as I tell my 7 yrs old ...a flashlight) and a light is something you see with your eyes and not necessarily "hear with your ears." Although I do believe if the door is open for a discussion, there is an appropriate time and approach to any topic. I am usually comfortable sharing what I believe in and why I believe it but, this approach for me was a challenge where I was able to really ask myself " Will people know I am a Christian without me having to say anything?" I take that train of thought with a quote from Billy Graham who said "share your faith, and if necessary use words". I really wanted to share it first by my actions and then (and only then) if there is an open door share with my words. So, I propose the question to all. What does it mean to be a Christian? I know a question like this can spur on some intense emotions and all I ask is that whatever your opinion is , you share it constructively. Please respond in the comment section. Thank you!  (participating in Pour out Your heart through thingsicantsay!)