Here I am 50+ years old, a preacher of the gospel for more than half of that time, and still discovering some of the simplest messages in the Scriptures.
I have always considered the parable of the laborers as a lesson of the equity of reward for all who obey the gospel, i.e., those who obey late in life receive the same reward as those who served the Lord all their lives. But I think I missed the main point. In fact, I’m sure of it as verse 16 summarizes the main thought, “Sothe first shall be last and the last first. For many are called but few are chosen.”
Also, note the last verse of chapter 19, “But many who are first will be last, and the last first.
Finally, note the first word of the first verse in our reading today. “For” is an explanatory introduction.
It now seems to me (and I certainly realize I could be wrong… again!) that the text is conveying the idea of serving God in faith. Going back to chapter 19 beginning in verse 23, Jesus explains that the Rich Young Ruler could not be saved because he was unwilling to serve God out of faith. Instead, he chose the temporal security of riches as opposed to the eternal security of faith (cf John11:25-26).
In Matthew 15:25-27, the disciples are confused as to who can be saved, and Peter inquires as to what will be their reward, seeing as they have left all behind to follow Jesus. Jesus promises that not only they, but all those who serve in faith, will be blessed in this life and inherit eternal life (15:29), concluding with the first of His “the last shall be first” statements.
Moreover, there may be some instruction for the Jews and their faith in the law versus the Gentiles and their faith in God and the Lord Jesus (cf Acts 26:20-23). “The men who bargained (the Jews? TC) were paid according to their bargain; the men who trusted (the Gentiles? TC) got far more that they could have dared bargained for” (Marcus Dods).
We are in no position to bargain with God. As we can see here, we are far better off to accept in faith His gracious invitation to labor in His vineyard, trusting that we shall receive from Him “whatever is right.”
This parable is not about equity of reward; it is about serving in faith.