because of this warning:
Matthew 7:21 Not everyone saying to me, Lord, Lord, will enter into the kingdom of the heavens, but the one doing the will of my Father who is in the heavens will. 22 Many will say to me in that day, Lord, Lord, did we not prophesy in your name, and expel demons in your name, and perform many powerful works in your name? 23 And yet then I will confess to them: I never knew YOU! Get away from me, YOU workers of lawlessness
Jesus is speaking about christians here. He is speaking about those who 'knew' him, but who failed to be found approved by Jesus. Not all forms of christianity is approved, we should never be blaze about that. If you care about your life and if you love God, you should want to be sure that you dont find yourself among one of these groups whom Jesus said 'he never knew'