Piety of every person is not the same. Two men graduated from the same university, studying the same subject (Islam) turn out to have different piety, points of views and behavior. Even Al Qur'an scholars have different piety and attitude. What causes the differences?
There is a true experience when an ustadz (religious teacher) of a boarding Islamic school asked ten of his students came to him. He wanted to know the result of the Islamic studying of his students. The teacher gave each of the students a pigeon.
"Please find a place where nobody can see you and slaughter the bird I just gave you. After that, come back to me bringing the dead pigeon," he ordered.
The ten students ran to find hidden places to slaughter the birds. After slaughtering, the students came back to the teacher and showed their work. It turned out that all students slaughtered the bird except one student. The teacher asked him why he didn't do what he was asked to do. The student answered, "I tried to find a place where nobody can see me. I couldn't find it, because wherever I go, I believe that Allah (God) sees me all the time. So, I didn't slaughter this bird."
Those ten students studied the same thing for years with the same teachers. However not all of them did the same thing. Thus, knowledge does not determine the behavior or deed. So, what drives the action or behavor? It is belief. The belief that God is always watching had prevented that one student from slaughtering the bird. Such a belief is called Godly belief.
Knowledge and belief is just like flour and bread. Eating flour doesn't make a person full but eating bread does.
Flour <——————> Knowledge
Bread <—————–> Belief
Getting full <——————-> Behavior, attitude, action
However, knowledge is important because it is the raw material for obtaining belief in our heart or soul. God says in the Qur'an chapter 20 verse 114: "So high [above all] is Allah , the Sovereign, the Truth. And, [O Muhammad], do not hasten with [recitation of] the Qur'an before its revelation is completed to you, and say, "My Lord, increase me in knowledge." Also in chapter 39 verse 9: "…Say, "Are those who know equal to those who do not know?" Only they will remember [who are] people of understanding."
But, if knowledge is not 'cooked' or processed further to become belief, then the knowledge that we have will not give benefit, meaning the knowledge will not lead to action or behavior.
If a person takes Islam simply as a knowledge, that person will not behave according to the rules of God in the Qur'an. That's because Islam will be just a bunch of information that he puts in his brain. He knows but he doesn't believe. Meanwhile, if a person takes Islam as a belief or faith, he will put all the teachings in his heart or soul, resulting in parallel attitude.
Knowing that God exists will not make a person prays five times a day and fast. But believing that God exists will make a person obeying the command of praying and fasting. Knowing that life is a test from God will not make a person patient. But believing that life is a test from God will make him patient in facing all the problems in his life. Knowing that Islam is the only religion approved by God will not make a person stay in Islam. But believing that Islam is the only religion approved by God will make a person stay in Islam forever and will not convert to other religion. Knowing that taking other things as god is unforgivable sin will not make a person stop 'worshipping' money and job position. But believing that taking other things as god is unforgivable sin will prevent a person from 'worshipping' money and job position. And knowing that doing bad things is actually booking a place in hell will not stop a person from lying, stealing, doing corruption, and cheating. But believing that doing bad things is the same as booking a place in hell will definitely stop a person from doing bad things.
Now, which one is more important? Having a great amount of knowledge or Godly belief? It is clear that piety or good behavior or good deeds is the result of having many Godly beliefs, not the result of having an abundant of knowledge. Piety, good behavior, good deeds are the result of having an abundant of Godly belief is the heart or soul, not the result of an abundant of knowledge in the brain. Therefore, our priority as a human being, as a creation of God is to gain as many Godly beliefs as possible.
Remember the saying of the Prophet, "knowledge without action is like lightning and thunder without rain." Having knowledge about Islam is not enough to produce piety or good deeds. In the sight of God, the best people are not those who are rich in knowledge but who are rich in piety or good deeds as God says in the Qur'an chapter 98 verse 7, "Those who have faith and do righteous deeds, they are the best of creatures .