What is a Christian?
  The gospel of grace proclaims that all people everywhere are included in Christ. What then is the difference between a Christian (believer) and a non-Christian (non-believer)? Answering this question begins by noting what is common to all people:      All are "in Christ."  The eternal Son of God, our Creator and Sustainer, became through his incarnation the  vicarious  (representative - substitutionary) human being .  Paul refers to Jesus as the second (last) Adam,  who stands in for all people (Romans 5:12-21) and is the fountainhead of a new (re-created) humanity (2Cor 5:17). Because of what Jesus has done in union with all humanity, all people are now reconciled to God (Col 1:20, 2Cor 5:19a).   Jesus became human for us all; taking on our nature and thus becoming sin for us (2Cor 5:21). When he died it was thus all of sinful humanity that died with him, and all sin was atoned for through him and in him (Romans 6:10; 2Cor 5:14-15).   Then when Jesus ros...