After a lot of thought over a period of time, I have come to the conclusion that the notion that one develops himself spiritually over time until he glows in the dark, is not a Biblical concept.
In fact, it is not about us at all. We don't become better people as we grow in grace. We remain the same in ourselves. What does develop is our increasing dependence on the promises of God and the teaching that the Holy Spirit gives us. The gifts of the Spirit never belong to us, nor are they extensions of our ability. They are the outworking of the ability of the Holy Spirit as we work in cooperation with Him.
In fact, instead of developing into super-Christians, which is all about self, we develop our faith in the sufficiency of God's Word and the Holy Spirit to do the work that He empowers us to do. The idea of developing ourselves spiritually is New Age. It takes the glory away from Christ because it can give the impression that as a super Christian I can accomplish great things through my own spiritually developed ability. This was the problem with those who Jesus refused to acknowledge at the Judgment. "Have we not prophesied, cast out demons and done mighty works in your name? Jesus replied: "I never knew you. Depart from Me you workers of iniquity." This is because the ones rejected by Christ have put the emphasis on "me, me, me" by thinking that power with God comes from puffing themselves up in some kind of New Age spiritual development until they just about glow in the dark. They think it is because of their own superior spirituality or holiness that achieves success in their lives and ministry.
This is the self deception in a person who dresses himself in a white suit and thinks he has a special anointing where no one can touch him - that he is above guidance and correction and accountable to no one but himself.
Jesus said that we need to become like little children if we are to inherit the kingdom of God. A child is totally dependent on his parents and caregivers. This is what a childlike faith is all about. "We have the sentence of death in ourselves that we should not trust in ourselves, but in God who raises the dead."
King Saul was secure in his role when he was "little in his own eyes". But when he started thinking he was somebody, he fell out with God and ended up losing his kingdom and his life, and took some good people down with him.
Solomon had the right idea. At the end of his life, he concluded that "all is vanity". This was in spite of his great wisdom, which was a gift from God rather than any personal development; and his accomplishments and his wealth. He had risen to the top, and yet in the final analysis, all he could look for was the grave.
So I conclude that the quest for greater spiritual development in ourselves is a road to nowhere.