Here is the ultimate explanation for why some are present at the wedding feast and others are shut out. Christ does not hide this.
We preach to all, but we have the assurance that those who are predestinated to life will respond to the message, so that our preaching will not be in vain. We rely on the effectual call of the Spirit to do what we cannot do and so we are co-workers with God in the greatest task that can ever take place in the world.