"You are not a Christian because you lead a Christian lifestyle. Rather you lead a Christian lifestyle because you are a Christian. There are tens of millions of religious people in this country of ours and countless millions in other lands, who are staking their eternity upon the notion that they are Christians because they try to lead a relatively Christian lifestyle.
But if that were possible, why do you suppose the Apostle Paul, the greatest Christian theologian and missionary of all time, would have spent three chapters talking about justification before he ever got to the subject of how to live the Christian life?
The simple truth is that you can imitate a Christian life, and you can fake a Christian life, but you cannot really live a Christian life until you are one."
(from "A Call to Holy Living" by Michael Andrus )
