The Disney movie "All Dogs Go To Heaven" gets at the idea more than we would like to think. The idea it gets at, in the end all people go to heaven. A great universalist doctrine, which has little standing when we actually read the Scriptures. Matthew 13 is pretty much an exclusive teaching by Jesus about what the Kingdom of Heaven is like. While everyone has a chance to participate in the Kingdom, Jesus makes it clear than not everyone will experience the fullness of the Kingdom.
Some of the seed will be snatched away, some will grow and wither, while some will grow and get choked by thorns, only a portion of the seed will grow and bear fruit. Likewise the wheat and the weeds will grow together. The reality, some will follow God and others will follow their own way. Those who follow God through Jesus Christ will experience the fullness of the Kingdom of God. This means some will be left out. This is not something that is being taught by human minds, rather from the very heart of God.
Jesus even addresses the religious people, and the fact that just because they are religious does not mean they will enter the Kingdom. In today's terms this means that just because you darken the door of the church, and talk about God, does not mean you will experience the Kingdom. Not all dogs go to heaven, and not all people experience the Kingdom.