Grow in grace, and in the knowledge of our Lord and Saviour Jesus Christ. 2 Peter 3:18.
Although you may be born again, it will require time to become a full-grown Christian. Justification is instantaneous, but sanctification is a lifework. We are to grow in wisdom. We are to add grace to grace. A tree may be perfect in its first year of growth, but it has not attained its maturity. So with the Christian: he may be a true child of God, but not a matured Christian.
Taken from the book Day by Day with DL Moody DL Moody 1837-1899