Such a mistake not only hinders spiritual progress but makes the voice of God in the soul only the voice of a doubting conscience. Instead of advancing God's glory, this brings dishonor to His name. This is sin any way one looks at it. No one in any state of grace is exempt from the possibility of willful sin in this life. The second biblical witness that sin is a falling short of a mark is likewise relevant in today's society.
Sanctification is infinitely more than crisis.
It is also progress. There is need for all emphasis upon growth in Christlikeness in this life. All holiness admits of growth. That is, blessed is the one who sees the need of growth. To know of the possibilities of growth and to fail to progress in that growth is to miss the mark-it is to sin.