Bible references: John 8:31, Matthew 28:19-20
The word of God serves as food or in other words nutrition to the spirit. This means that the purpose of studying the Word of God is in other to enable our spirit grow. Growth is a continuous process. As long as we want to keep growing in our spirit man we need to maintain continuous involvement in the study of God's Word.
The day we stop learning that is the day we stop growing spiritually. In the program of God there is always more that is available. We do ourselves a lot of good when we maintain consistent study of God's Word. No matter how much we think we know already, there's still a lot more that we can know.
John 8:31 - Then said Jesus to those Jews which believed on him, If ye continue in my word, then are ye my disciples indeed
Jesus wants for us to continue in His word and not to stop halfway. The Word of God is so important that even the devil is knowledgeable about it as we seen in Matthew 4:6. This is why it is important that we hold firm unto the Word of God so that we know how to counter the enemy when he comes at us with his evil schemes.