In Hebrews 5:13-14 we see that,
"For everyone who partakes only of milk is not accustomed to the word of righteousness, but he is a babe. "But solid food is for the mature, who because of practice have their senses trained to discern good and evil."

We are all works in progress. No one has arrived yet, but as the song goes, "From glory to glory He's changing me, Changing me, changing me. His likeness and image to perfect in me, The love of God shown to the world.

For He's changing me, changing me,
From the earthly things to the heavenly.
His likeness and image to perfect in me,
The love of God shown to the world." (Composer unknown)

Scripture exhorts the seeking of spiritual maturity:
By putting away childish things:
"When I was a child, I used to speak as a child, think as a child, reason as a child; when I became a man, I did away with childish things." Says the Apostle Paul in 1 Corinthians 13:11

By cultivating understanding:
"Brethren, do not be children in your thinking; yet in evil be babes, but in your thinking be mature." 1 Corinthians 14:20

By striving after Christlikeness:
"Until we all attain to the unity of the faith, and of the knowledge of the Son of God, to a mature man, to the measure of the stature which belongs to the fullness of Christ." Ephesians 4:13

By partaking of the deeper truths of the Gospel:
"But solid food is for full grown men (and women), for those whose senses and mental faculties are trained by practice to discriminate and distinguish between what is morally good and noble and what is evil and contrary either to divine or human law." Hebrews 5:15 The Amplified Bible (My parenthesis)

By overcoming temptation:
"...I have written to you, young men, because you are strong, and the word of God lives in you, and you have overcome the evil one." 1 John 2:14

Believers are to grow up:
Into Christ:
"But speaking the truth in love, we are to grow up in all aspects into Him, who is the head, even Christ." Ephesians 4:15

In Love:
"And the Lord make you to increase and abound in love one toward another,and toward all men, even as we do toward you." 1 Thessalonians 3:12

Through the Word:
"Like newborn babes, desire the sincere milk of the word, that you may grow thereby." 1 Peter 2:2

By increasing in godly characteristics:
"...Giving all diligence, add to you faith virtue; and to virtue, knowledge; and to knowledge, temperance; and to temperance, patience; and to patience, godliness." 2 Peter 1:5-6

In grace and knowledge:
"But grow in grace, and in the knowledge of our Lord and Savior Jesus Christ. To Him be glory both now and forever. Amen." 2 Peter 3:18

It was Jesus who said in Matthew 5:48,
"Therefore you are to be perfect, as your heavenly Father is perfect."

From glory to glory so shall it be as we yield, in trust and obedience, to Christ Jesus by the power of the Holy Spirit as ordained by our Heavenly Father! All honor and glory are Yours, Lord God Almighty! Amen