They thought that they were doing the right thing.
Jesus was busy. He had important things to do and important people to see. No one asked these people to bring their children to Jesus, so the disciples let them know that they were not welcome.
In fact, the Bible says that they rebuked the parents. Rebuke is one of the harshest words used in the word of God. The Merriam-Webster Dictionary says that it means “to criticize sharply.”
However, Jesus turned and said, “Let the little children come to me, and do not hinder them” (Luke 18:16).
Later on, as they were entering the town of Jericho, a blind man began calling out to Jesus. Again, it says that the disciples “rebuked him.” In those days, people believed that physical problems were the result of sin.
Therefore, either this man, or his parents, had done something that caused God to punish him, so what right did a “sinner” have to call out to Jesus? However, “Jesus stopped and ordered the man to be brought to him” (Luke 18:40), and He healed him.
Another time, John said, “Master, we saw a man driving out demons in your name and we tried to stop him, because he was not one of us” (Luke 9:49). Jesus replied, “Do not stop him, for whoever is not against you is for you” (verse 50).
In each of these cases (and several more), the disciples had the wrong picture. They thought that they were to be gatekeepers. They thought it was their job to make sure that only the right people got in and that the rest were kept out.
Jesus, though, does the exact opposite. Instead of keeping people out, he constantly invited them in.
In Matthew 13, Jesus tells two stories that apply here. In the first, a farmer sows a field, but an enemy sows weeds in it. The servants want to pull the weeds as soon as they show up, but the farmer says, “No! Let them grow and we will sort them out at the harvest when we can tell which plant is really a weed and which is the wheat.”
In the second story, a fisherman throws his net in the water and catches all kinds of fish. Then he goes back to the shore and he sorts the good from the bad. The sorting is not attempted until the end.
The point: we are not gatekeepers that keep people out of the kingdom. It is not our job to sort the good from the bad. Our job is simply to say “Come.”
God will do the sorting at the appropriate time.