“will do his will” (KJV) = literally means “is willing to do His will”. The NIV renders this as “chooses to do God’s will”.

“The fundamental condition for obtaining spiritual knowledge is a genuine heart-desire to carry out the revealed will of God in our lives.” (Pink) We can never understand God’s Word or receive spiritual discernment if we are not willing to obey it when we receive it. God does not waste the revelation of His Truth on those who don’t believe and won’t act upon what He tells them. His Word is a lamp to our feet and a light to our path (Psalms 119:105), but only if our feet are on the path and we are willing to walk it.

Psalms 119:105  Nun Your word is a lamp to my feet and a light for my path.

God never gives us knowledge just for knowledge’s sake. Learning by itself just brings pride (1 Cor 8:1) and education can be a god if it competes with God Himself.

1 Cor 8:1  Now about food sacrificed to idols: We know that we all possess knowledge. Knowledge puffs up, but love builds up.

Also, if we go to God’s Word with a wrong attitude, He will not enlighten us. If we are studying His Word to prove our own doctrines (which would be the doctrines of men), then we will indeed prove them, but they will not be truth. We can easily deceive ourselves, especially when we want so desperately to believe a certain doctrine, but when we are willing for God to show us whatever He wants and our willingness is so strong that we will do His will irregardless of what it is, then we have freed Him to reveal His Truth to our hearts and to give us the assurance that what He has shown us is indeed true.

Spiritual knowledge does not come through our intellect, but through our hearts.

The doing of God’s will involves faith (John 6:29). Without faith it is impossible to discern the validity of the teaching of Jesus. Augustine writes that “understanding is the reward of faith. Therefore do not seek to understand in order to believe, but believe that thou mayest understand…what is ‘If any man be willing to do His will’? It is the same thing as to believe.”

John 6:29  Jesus answered, “The work of God is this: to believe in the one he has sent.”

Again, spiritual knowledge does not come through our intellect, but through our hearts. We don’t receive it by studying, but by exercising our faith (Heb 11:3). God is knowable if we press on in faith with a desire to know Him and a willingness to do His will (Hosea 6:3).

Heb 11:3  By faith we understand that the universe was formed at God’s command, so that what is seen was not made out of what was visible.

Hosea 6:3 (NAS95) “So let us know, let us press on to know the LORD. His going forth is as certain as the dawn; And He will come to us like the rain, Like the spring rain watering the earth.”