It's been said that Religion is man's attempt to reach God, while Christianity is God's attempt to reach man.  By this admittedly limited definition people use religion to justify themselves-by works, rituals, organizations, or personal denial-in hopes of being good enough to earn God's favor and blessings.  Christianity, quite the opposite, is God justifying those people he has chosen-totally apart from any worthiness on man's part, or any obligation on his part to do so.  It's Jehovah God doing all the work, paying the full price, and completing the transaction to make the way-through active acceptance of his gracious offer-for man to receive all the benefits of being in right relationship with his creator. 

Christianity is a personal one-on-one relationship with the creator of the universe.  It doesn't depend upon belonging to the correct organization, being the right nationality or ethnic group, being in the right place at the right time, paying enough money, or sacrificing enough time.  You can't earn it by following a set of rules, acknowledging some formula, following a specific leader, or foregoing certain foods, activities, or other external things.  "God loves, accepts, and values you on the basis of Christ's performance at the cross and not on the basis of your performance!  ...we cannot do anything good to cause god to love us more, and we cannot do anything bad to cause God to love us less" [Holt, Liberating Grace and The Performance Treadmill].

The United States is called a Christian nation.  Some Christian faction is fighting someone somewhere.  The Christian coalition champions some political candidate or social agenda.  But none of these are truly Christian in the true Biblical sense.  Christians may belong to these groups, or these organizations may have once been based upon, or are advocating, Christian principals or ideals; however, this doesn't make them Christian.  Only individuals can be Christian.

Biblical Christianity is any individual's willful decision to accept God's offer of a favorable, eternal relationship--based solely upon what Jesus Christ has already accomplished on that believer's behalf.  The Bible describes this relationship many ways, but most vividly uses the analogy of adoption to describe God selecting children who once rightfully were children of the Devil and making them part of his own righteous family.  He does this as a free, gracious, act of His love, and we respond by trusting in his means of accomplishing this adoption--Jesus the Messiah.