The Kingdom of God belongs to children, and presumably to those who will humble themselves like little children and faithfully follow Him. Jesus commands that the children be “let alone,” not bothered or hindered. There is much in our society today that IS hindering them.
The rich young man who came to Jesus wanted a quick fix, or a way to work his way into heaven. Jesus told him that was impossible. It has to be done God’s way (see John 3:16). Jesus said that we must be obedient to God’s commands and named five of the Ten Commandments followed by one of the two commandments He gave elsewhere which He said sum up the entirety of the Law: Love your neighbor as yourself (the other is: Love the Lord your God with all your heart, mind, soul, and strength). It is impossible for man to get into heaven on his own, but with (through) God ALL things are possible.