How often have you hear people saying things like, "I've put myself out for you, now what are you going to do in return?"
Today's gospel passage seems easy enough to understand at first light, if we compare the characters in the parable to key figures in the history of salvation.
We have the king and his son, representing God and Jesus. The wedding can be compared to God's own invitation to us all to follow him and his way, entering into communion with him just as wedding guests share in the festivities.
And the messengers that were sent out to announce the wedding -- they represent the prophets. Similarly to many of the prophets working for the Church, these messengers were also badly treated by the people to whom they were sent.
And what of the people themselves, those people who turned down the wedding invitation? They represent the people to whom the original invitation to follow God was shown -- and just as many people in real life turned away from God for whatever reason so they did in the parable.
So enter the alternative people, those who were found at the crossroads. Jesus is referring here to any category of people who did not make up polite society in those days, and letting his hearers know that the message of the Kingdom of God is now open to absolutely anyone. After all, we read that the servants went out to collect together 'everyone they could find, bad and good alike'.
So whereas the 'proper' people had been invited at first, due to their refusal sinners are now invited. This gives hope -- both for nowadays, when we know ourselves to be at odds with the Gospel message (and therefore sinners) at times, and also in those times -- for perhaps there were those hearing the invitation who took it to heart and acted accordingly.
Once having accepted the call to follow God, however, we cannot stop there just resting on our laurels, saying, "I have been invited by God to the Kingdom of Heaven. And that's it!" Because once we enter into a relationship with God, we are called to go ever deeper into relationship with Him, and that implies that we do not and cannot sit still, doing nothing at all.
Fair enough -- but what about the remainder of the parable? An initial reading of this parable can seem puzzling, because once someone has been called and accepted by God, just as the guests eventually joined the wedding banquet and joined in all the feasting, wouldn't that be it? Not at all, is the answer.
The key word here is 'wedding-garment'. For in the days when this parable was first told, whatever state of life you found yourself to be in carried certain obligations - correct behaviour or observance of wedding customs applying to all, no matter what.
And this guest has no wedding garment. In other words he is not bothering to do something fundamental to his state in life, not bothering to observe the customs he should, neither growing nor working towards a closer relationship with God in his life.
And so it was with the king at the wedding feast. He had put himself out for the guests, but that implied they should put themselves out for him. Not doing so, and not even explaining or apologising shows a lack of concern or desire to follow what God has asked us to do.
Compare that with daily life, and you will see that God's call is clear -- it is not enough to be called and accept that call, but there is the obligation to follow it in whatever way we are called to do. In that way, we are acknowledging what God has done for us, and we are doing whatever we are called to do in return.
In other words, not only have we been called, but also (as a result of our actions) we are being chosen by God to share in his eternal wedding feast in heaven.