Christianity is God. Christianity is truth. Christianity is the glorification of God through the glorification of man.
What is Christianity? It’s God getting man to where man is supposed to be: in his glorified state. Adam and Eve were not in the glorified state of man before the fall… they were, if I might use the term, in a ‘neutral’ state. They were neither fallen, neither were they righteous. When the fall occurred however, man went from the neutral state a step down to the fallen state. Christianity is God getting man out of his fallen state to his glorified state. Christianity is firstly about justification and sanctification and the resurrection. Those are the three essential tenets to Christianity, and that’s essentially what it is at it’s root. I don’t think you can really get more basic than that…