We are all growing to maturity and none of us is there yet, as we forsake what is behind and make our eyes single for the purpose of laying hold of what lays ahead of us. The only problem a believer may have is only if he refuses to grow in Spirit and grace, growing in the spirit involves studying the word of God, people and circumstances. The word of God provides the knowledge of God, His will and guidance on how to live the Christian life, while the people provides the support needed to the life expected of you and the circumstances provides the necessary environment to practice Christianity and become Christ like. All these definitely facilitates growth.

Till we all come in the unity of 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.
Ephesians 4:13