It is the same in the spiritual. When we are born again of the water and the spirit, we become a child of God; however we have a lot of maturing to do. The Bible gives us some instructions on how to grow spiritually.
We must humble ourselves as a little child. Matthew 18:3-4 says “Verily I say unto you, Except ye be converted, and become as little children, ye shall not enter into the kingdom of heaven. Whosoever therefore shall humble himself as this little child, the same is the greatest in the kingdom of heaven.”
We must study His word. I Peter 2: 2 says “As newborn babes, desire the sincere milk of the word, that ye may grow thereby.”
II Peter 3:18 says ‘But grow in grace, and in the knowledge of our Lord and Savior Jesus Christ.”
We must grow in faith and charity. II Thessalonians 1: 3 says “We are bound to thank God always for you, brethren, as it is meet, because your faith growth exceedingly, and the charity of every one of you all toward each other aboundeth;” Matthew 17: 20 tells us that if we have the faith the size of a mustard seed, we can move a mountain and nothing will be impossible for us. In Matthew 13: 31-32, Jesus tells this parable: “The kingdom of heaven is like to a grain of mustard seed, which a man took, and sowed in his field. Which indeed is the least of all seeds; but when it is grown, it is the greatest among herbs, and becometh a tree, so that the birds of the air come and lodge in the branches thereof.”
We must build upon the foundation of the apostles and prophets; Jesus being the cornerstone of the building. Ephesians 2: 21 says “In whom all the building fitly framed together growth unto a holy temple to the Lord”. Jesus gave us ministry thru apostles, prophets, evangelists, pastors and teachers for the perfecting of the saints. All of these are to help us grow. Ephesians 4: 14-15 says “That we henceforth be no more children, tossed to and fro, and carried about with every wind of doctrine, by the sleight of men, and cunning craftiness, whereby they lie in wait to deceive; But speaking the truth in love, may grow up into him in all things, which is the head, even Christ:”
Peter tells us in II Peter 1: 5-8 that in order to grow, we must continue to add things. “And beside this, giving all diligence, add to your faith virtue; and to virtue knowledge; And to knowledge temperance; and to temperance patience; and to patience godliness; And to godliness brotherly kindness; and to brotherly kindness charity. For if these things be in you, and abound, they make you that ye shall neither be barren nor unfruitful in the knowledge of our Lord Jesus Christ.”
So children of God, let us grow in the knowledge of Jesus Christ, making our calling and election sure. For if we do so, we will never fall and according to II Peter 2: 11 “an entrance shall be ministered unto you abundantly into the everlasting kingdom of our Lord and Saviour Jesus Christ.”