"When I was a child, I spake as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things" (I Corinthians 13:11).
The apostle Paul's admonition to believers is to put away childish things. Childish speaking, childish thinking, and childish reasonings are to be put away.
Children are basically selfish. They develop a "me first" attitude and can even become quite greedy. These traits are carried over into adulthood. "For men shall be lovers of their own selves, covetous" (II Timothy 3:2).
Children are capable of having temper tantrums in which they scream and kick and fight; becoming quite aggressive when not getting their way. Christians have been known to act this way as well. "Let all bitterness, and wrath, and anger, and clamor, and evil speaking, be put away from you, with all malice" (Ephesians 4:31). "From whence come wars and fightings among you? come they not hence, even of your lusts that war in your members?" (James 4:1).
Due to a lack of discernment, children are not always aware of danger. Even so with adults, "know ye not that the friendship of the world is enmity with God?" (v.4). "See then that ye walk circumspectly, not as fools, but as wise. . . . Wherefore be ye not unwise, but understanding what the will of the Lord is" (Ephesians 5:15,17).
God's will for the believer is spiritual maturity. "Brethren, be not children in understanding . . . but in understanding be men" (I Corinthians 14:20).
"Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect [mature] man, unto the measure of the stature of the fullness of Christ: That we henceforth be no more children. . . . But speaking the truth in love, may grow up into Him in all things, which is the head, even Christ" (Ephesians 4:13-15). NPS