In Matthew chapter 18, Jesus' disciples came to Him and said, "Who then is greatest in the kingdom of heaven?" And Jesus called a child to Himself and set him before them, and said, "Truly I say to you, unless you are converted and become like children, you will not enter the kingdom of heaven. Whoever then humbles himself as this child, he is the greatest in the kingdom of heaven."
Jesus is telling us to become like children spiritually by imitating good aspects of them. Then, let's delve into how we can achieve this heart and mind of a child.



A spiritual child's thoughts and actions are simple and uncomplicated

The thoughts and actions of a child are not complicated, but simple. So, they accept what they are taught. In the same way, if we become like children, spiritually, we plainly obey the Word that tells us 'to do', 'not to do', 'to keep', and 'to throw away' something.
On the contrary, one who has the heart of an adult tends to judge the Word of God with his own standards, listens to only what he wants to hear, and obeys only what he thinks he can do. He does not accept others' thoughts and does not understand their actions in goodness, but he sees them through his own way of thinking. Since he sees them within what he deems appropriate by his knowledge and mindset; he misunderstands, judges, and may even condemn them.
Such men do not believe the biblical works of God and do not accept signs and wonders such as the sun and the moon standing still, the Red Sea being parted, and water coming forth from a rock with a strike.
Moreover, they cannot obey the Word of God since it tells them to serve others; humble themselves; turn their left cheek to the one who slaps them on their right cheek; give their coat as well to the one who wants their shirts; and go two miles with whoever forces them to go one.
God wants His beloved children to simply obey His Word the way a child would obey. In Abraham's case, he neither stated the reason nor resorted to excuses for disobeying when God told him to offer his only son, Isaac as a burnt offering. When God commanded him to do it, he immediately obeyed with trust in God's good will.
To become a great man in Heaven, we have to learn the truth, believe what we learn, and obey it just as a spiritual child does.


A spiritual child's heart and mind are pure

When we say something is 'pure', it means it is 'not mixed with anything else'. In other words, having a 'pure heart' indicates that the heart does not have anything evil or unclean in it. One with a pure heart reacts sensitively even to little things.
For instance, a child who is pure laughs and cries readily. When others dance and sing, he tries to mimic them. He laughs easily when comforted though he once felt resentful. If his brothers or sisters get swatted for their wrongdoings and cry, he cries together with them. When his mother is sick, he feels sad.
On the other hand, adults, who are not pure, feel numb about things (Luke 7:32). This is because they have been stained with the worldly things and untruth as they lived in the world. Meanwhile, their hearts have been hardened and feelings have become numb.
However, spiritual children are touched by things that belong to goodness even if it is a small thing because they are pure in heart. So, they have an earnest longing for God's works and their hearts continue to be moved by the testimonies they hear although they hear them repeatedly. They feel sensitivity to evil or untruth, so they feel a strong qualm of conscience when they do something wrong.
On the other hand, a spiritual 'adult' has a guilty conscience to a lesser degree than a spiritual child, even when he commits evil. To the extent that one is stained with the untruth he will be less sensitive about evil even while he is acting in evil. Some believers become like adults spiritually as time passes in their Christian lives. Although they seem to diligently lead a Christian life, if they continue to compromise, they will become de-sensitized concerning sins and become increasingly lenient in their attitude. Such people forsake grace simply if things do not seem to fit in their benefit and they act as they please. Rarely will they fight against sins to the point of shedding blood.
1 Peter 2:2 reads, "Like newborn babies, long for the pure milk of the word…" God wants us to become like new born babies spiritually and long for the truth and spiritual things. This is because the best kingdom of Heaven, New Jerusalem, is where only those who have pure and clean hearts like children can enter.


A spiritual child is not arrogant

Children do not insist on their opinions and do not want to be lifted up. For instance, if they are faced with something they are unable to do, they ask for adults' help. This is because they think they have less knowledge and power than adults. So, their pride is not wounded when requesting an adults' help—it just seems to be the natural thing to do for them.
Spiritual children are the same. They humble themselves before little ones as well as before God and they serve others. They do not insist that they are right and they confess from the heart that they can do nothing unless God is with them. Naturally, they do not judge or disobey the Word of God, but they just obey it.
1 Peter 5:5 reads, "…for God is opposed to the proud, but gives grace to the humble." The humble listen attentively even to a little one, and through the conversation, they discover and change themselves. Since they deem everybody more important than themselves they can serve others and count on the wisdom and strength of God without using their own way or thought no matter what they do.
Therefore, if anyone comes forth before God after having laid down his own experience, wisdom, wealth, fame, authority, and position, he can experience God's amazing wisdom and power.