If the man continued to surrender his deficiency to God, then yes, the man's faith would have continued to mature. But that is not the main lesson to be learned here. That main lesson is the fact that Jesus definitely set a condition upon His answering the man's request in his hour of great need. That condition was possessing faith. But the man confessed to being at least partially lacking in his faith as pertains to his son's deliverance. However, the man did posses full faith pertaining to another situation; namely, he had full (acceptable faith) that if he surrendered his deficient faith (as pertains to his sons's healing) to Jesus, then Jesus would take care of any "un-faith". Do you see? The man did have faith; faith that Christ is faithful in overcoming any "un-faith" the man was struggling with pertaining to his son.
It took faith in Christ for the man to surrender his un-faith (or lack of faith pertaining to his son) to Jesus.
Jesus set the condition for the deliverance; He delivered the son; therefore the condition was met.
(Jesus did not deliver the son just for the son and his father's sake, the deliverance also came for the sake of those gathering around the man (Mark 9:25). Christ wanted to bring glory to God through this event, just as He wants your life to glorify God and the Gospel.)
But we must understand that it is God's will for our faith to continue to mature (2 Peter 1:5) through other means once the foundation for such continued maturity is met. Surrendering our lack of faith to Christ is but the beginning. When we surrender our deficiency to Christ, he will then supply us with other knowledge concerning the means to grow and stabilize our faith to provide for greater consistency and assurance. Surrender is just the first step; the foundation of such continuing maturity. For example, if you do not come to fully understand the nature and purpose of God's written Word, then you will have future trouble with your faith. Therefore, the Lord will give you this knowledge so that your faith will mature as you are conformed to the image of Christ-likeness. Deficiencies are overcome; but we must surrender all such deficiencies. This is epitomized in how we first approached Christ: we surrendered our souls to him. And if you have all faith in believing that your sins were forgiven, and you trusted Christ with your greatest possession--your soul--then much more can you trust him with any deficiency in your faith pertaining to you current life situation and concerns. If God is faithful to preform the greater, then much more is He faithful to perform the lesser.
I am here for your edification. Stand firm in the faith delivered to you. This life's sorrows are incomparable to the everlasting glory awaiting you. Do not subject yourself to the elements of the world. If you abandon faith in Christ, then your alternative is faith in other things; for man/woman cannot live this life without putting extreme faith in either God, Satan, or man. You know what to choose.
Sorry for not providing all relevant scripture.
