Can you define Christianity without simply citing Bible verses to me? It's not just about your personal relationship with Jesus Christ - to say so sounds selfish. A relationship with Him is the heart of the spiritual body encompassing the whole belief. The body can no more live when separated from the heart than the heart from the body. To live, in loving Christ you must love others too, and in loving others you must also love Christ. With these you have established primary and secondary relationships, yet there is still a third.
Your tertiary relationship is about how you relate to the world. The body of the belief exists in life and cannot be truly separated from it except through spiritual death. So, then, Christianity must become your worldview in all aspects of reality. You cannot fracture the belief in order to have a separate secular one. Do you have two lives, one that Christ died for and the other He did not? You are either dead in the world or alive in Christ. We must properly define Christianity to the world because if we do not, the world will surely define us.