The image of having the door opened when one knocks is a cultural understanding. The phrase is mostly likely due to Matthew 7:7, “Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you.” The concept is certainly earlier, as it appears in the Song of Solomon, 5:2. It is a question of how well this particular image survived in the New World, as the custom is not clearly known. However, some form of petition to open a closed door or entryway was certainly in place.
Jacob continues to reflect on his own discourse. Here he reprises those who are wise in their own learning, and those who are rich according to the world. Jacob notes that these are things that should be discarded in order to enter into the narrow gate. It is probable that this was not hypothetical. It is very likely that this was directed at particular members of the congregation. Unless they repent of those two sins, they will be precluded from God’s kingdom.