5 If any of you lacks wisdom, you should ask God, who gives generously to all without finding fault, and it will be given to you.
Right after James states that perseverance needs to finish its work so that we would not be lacking in anything, he acknowledges that there are those who lack wisdom. The natural conclusion to be reached from the two statements is that if a person is lacking wisdom it is because they have not persevered through trials and temptations.
One should not expect wisdom to come unearned however. God gives us many things that we do not deserve, salvation being first and foremost, but given the context of the verses it appears that wisdom is given once it is earned through perseverance.
This harkens back to James 1:2 when he writes that we should consider it pure joy when we experience trials. These trials will lead to the wisdom that we seek. It certainly feels like a difficult road to travel and few people would intentionally ask for hardships in their life, but it is the manner in which wisdom is truly earned.
One might consider formal education in comparison to being granted wisdom by God. Earning a diploma or a degree requires work. It takes time, dedication, and sacrifice. If a person wants to be an engineer or a doctor or enter in any other line of work that requires a degree, they know in advance that they’ll have to put in the hard work required to reach their goal. It’s the same way with earning wisdom.
If a person wants to gain wisdom, God will grant it to them, but they’ll have to “go to school” through trials and temptations in order to be granted it. Fortunately God does not just enroll us in the school or wisdom, He’s also the teacher, the tutor, and the one who hands out the degree when it’s finished. He wants us to succeed and He will help us every step along the way so that we will pass the test.