Therefore every scribe who has become a disciple of the Kingdom of Heaven is like a head of a household, who brings forth out of his treasure things new and old. Matthew 13:52
Some become disciples of other men; some become disciples of a certain movement, denomination, or doctrinal emphasis. In the verse we have been studying about the scribes who become disciples, Jesus specified that these would become disciples of "the Kingdom of Heaven" (see Matthew 13:52). He was obviously emphasizing that they were not to become disciples of those on earth, or earthly things, but of His heavenly Kingdom.
Of course, the Lord appeared to Paul on the Road to Damascus, which will not happen to everyone. Even so, there is an aspect of Paul's conversion that must happen to everyone who would become a disciple of the Kingdom of Heaven – Paul had to be struck blind in the natural so that he could see spiritually.
This is not a statement against learning or even learning from a natural perspective. Some of Paul's previous learning, even in philosophy and other disciplines, later helped him to both understand and promote the Gospel. However, he first had to learn to see natural things through spiritual eyes, rather than see spiritual things through natural eyes. This is the key to being a disciple of the Kingdom of Heaven.
It took God knocking Paul off of his horse to break through what was truly blinding him. It takes God to do this for all of us, but it does not have to be as dramatic as Paul's experience to get the final result. It may be better the way most do it who attain to this – they humble themselves instead of having the Lord humble them. We are told that we can judge ourselves and the Lord won't have to do it.
Paul did not get spiritual vision immediately after he received his natural vision back. By his own testimony, we know that he went away into the wilderness for between eleven and fourteen years. Then after he was commissioned to the apostolic ministry, the transformation continued. We can see a great and continuing change in him over the span of his ministry. It will likely be a lifelong process for all, and this is why we must remain disciples of the Kingdom of Heaven our whole life.
Paul, who was so steeped in natural knowledge and training, may have taken a bigger jolt and more severe discipline than others to go through this transformation. Some seem to have a much more "natural" tendency to be spiritual and adapt to seeing from a spiritual perspective. The main point here is that we must have this transformation, and presently very few do. This is why we must become "disciples of the Kingdom of Heaven," not disciples of the earthly.