"A certain man made a great supper, and bade many: and sent his servant at supper time to say to those that were bidden, Come...." The man in the parable is, of course, our Lord, God, and Savior Jesus Christ, and the great supper is the feast of eternal joy in God's heavenly Kingdom, to be fully revealed at the end of time--a feast to which every soul ever born into this world is invited. For truly, God desires not the death of the sinner, but rather that he repent of his sins and return to the straight and narrow path of salvation.
Nevertheless, only those who have striven to mortify (put to death) their "members which are upon earth; fornication, uncleanness, concupiscence, and covetousness" are bidden by God to attend. As for the others: they have to one degree or another closed their ears to the Word of God, having of their own free will rejected the grace He so freely offers.
Yet even among those who have been bidden, the greater number have been so caught up in the worldly affairs of this transient life that their spiritual eyes have been so blinded to the truth that they fail to discern those "good things" that God has in store for those who love Him, and desire in their deepest heart to abide by His commandments. And so it is that these unfortunate souls (among whom, if I may be so bold, you and I are included), are forever making seemingly rational excuses concerning why it is simply impossible (at this particular moment of time) to fully forsake the false promises of this world and to enter into the ineffable joy of eternal salvation.
Make no mistake: even you and I are in grave danger of falling into this temptation, this delusion that our paltry worldly affairs bear any ultimate significance in the vast scheme of things. It is business as usual, you see, as in the days of Noah, and meanwhile the Great Flood--the inexorable judgement of God--is imminent. And yet the measure of the saints deemed worthy of God's Kingdom must be fulfilled before the end of this age.
And so it is that the Master of the house (our Lord, God, and Savior Jesus Christ) instructs His servant to "go out quickly... and bring in hither "the poor, and the maimed, and the halt, and the blind"--that is, the poor of spirit, the humble, who are deep down fully aware that they are unworthy to enter the Kingdom, and therefore they do not presume to make excuses. It is among these--the lowliest of the low, according to the wisdom of this world--that our Lord must compel to come in.
This is so not in the sense that He can violate a person's free will and force him to accept a salvation he has chosen to reject. We are all perfectly free to make whatever excuses we desire, ultimately spurning God's free gift. But if we are willing to acknowledge our weakness, casting ourselves at the feet of God without expectation and beseeching His mercy, we shall fully experience the truth of St. Paul's words, "the power of God is made perfect in weakness."