John MacArthur sums up the problem beautifully in his latest post: Inward, Upward, Outward? over at the Shepherd's Fellowship blog. Here is an excerpt:
"There is only one reason the Lord allows His church to remain on earth: to seek and to save the lost, just as Christ’s only reason for coming to earth was to seek and to save the lost. “As the Father has sent Me,” He declared, “I also send you” (John 20:21). Therefore, believers who are not committed to winning the lost for Jesus Christ should reexamine their relationship to the Lord and certainly their divine reason for existence.Fellowship, teaching, and praise are not the mission of the church but are rather the preparation of the church to fulfill its mission of winning the lost. And just as in athletics, training should never be confused with or substituted for actually competing in the game, which is the reason for all the training. "
I would only add that if one professes Christ and yet does not feel a love for the lost and a desire to share Christ with them, they can evangelise the lost out of a sense of "duty" or out of a motivation to somehow prove to themselves and/or others that they are "born-again" because they are outwardly doing what the Lord commands, yet inwardly they are still dead in their sins. So, we add "evangelism" to the list of outward expressions for what should naturally occur from an inward reality.
The important thing is not in the doing, but in the why we are doing, "the doing". I have found that lost sinners can detect the difference. It is almost as if God uses them to expose the hypocrisy of those who wear His name and yet inwardly are as dead, blind and lost, as those they are evangelising without His love dwelling in them.
I suggest that there is also a huge difference between someone who does feel a sorrow and love for lost sinners and desires to share Christ; but doesn't step up even when the Lord presents them with a perfect opportunity to do so; because they feel ill-equipped or are have a timid or shy temperament versus someone who has been raised in the church; professes Christ; is very equipped (in terms of knowledge of the Gospel) and yet feels no sorrow or love for the lost.