While working on a test or examination, a diligent student will strive to give correct answers to all the questions. That can be done, and, when it does happen, that student is very pleased. But what is more important is that we become perfect members of the body of Christ, His church. We do well to bear in mind that the church is His body, and He is the Head of it. Each of us has his divinely designed place in that body, and work to perform in it. The ear performs different work than the eye. The hand does what the foot cannot do. The stomach does not want the air which the lungs take in.
As members of the body of Christ we come from different nations, tongues, and tribes. We are of different colors and natures. It can be compared to the diversity found in the human body, in which the eyes differ from the ears, the lips from the hair, not only in color but in structure and in the work they are designed to do. But we all are one body with members that work together, not against each other. Thus Paul wrote in Ephesians 4:13 , "Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fullness of Christ."
This stands in close connection with the preceding verse which speaks of God edifying the body of Christ by making us perfect through the preaching of the truth. And what is so important is that we all have the same faith. Doctrines are true or false. They build us up spiritually, or they are poison which corrupts our souls.
What is so important then is that we know Christ as He truly is as the Son of God. We must know what he loves and hates, as well as how we can please Him, walking in love for God and hating Satan and the lie in whatever form it comes. We must want and strive to be perfect in the eyes of God, even as Christ is and always was that perfect.
Read: Psalm 119:33-48 .
On instruction: “The passing generation knew the Lord and His work for Israel… But the next generation knew not the Lord, neither the works He had done for Israel. …The conclusion from all this is plain: grow lax in instruction - in home or school or church - and the next generation will not know Jehovah and will not know His great works for His people.” -H. Hoeksema