Some think all will go to heaven, but Jesus says strive to enter thru the narrow door. You are liable be shut out if you don’t work towards entering the life with Christ after death. Our psalm implied there is nothing after death, here there is a narrow door, and Paul preached grace. It is a tension between justification and sanctification. After I received grace then I have to leave it out. God gives us many chances even if we keep failing. I can’t save myself by what I do. There is a mystery about this relationship and we don’t really know how this works. What about people who don’t believe in Jesus. What about Muslims and others who have other beliefs. God is God and will do what he wants to do. We can’t depend on works at all because they are tainted by sin. And then we have the spread of a mustard seed. Look at Jesus ministry has spread throughout the world. We don’t know the impact of some of our or other’s actions. He is talking kingdom of heaven which is our lives today, not some future by and by. Verses 28 thru 30 indicate an ongoing kingdom of God not necessarily in the immediate future. God doesn’t talk about the state of heaven and it may not be on a far off planet but just some sort of revitalization of our life here. Possibly it is more about the journey rather than destination. Worry about what you do here not what your future home will be.