We often think of Matthew 20:16 as a reversal of order. In the context of the parable of the workers in the vineyard, however, "the last will be first, and the first last" takes on a different meaning. The laborer hired late in the afternoon received the same wage as the laborer hired early in the morning. In this situation, the issue is not of hierarchy, but of equality.
In the body of Christ, the church, we are all equal. Whether our families have been church members for generations, or whether we have recently become Christians, we are all parts of the same body. We have, and we work towards, the same hope of the heavenly kingdom; therefore, we should not discriminate nor show favoritism. Rather, we should serve God and one another with love and humility.
Each worker in this passage received the same amount regardless of the number of hours he worked. In a spiritual context, this shows that the grace of salvation is given freely to all; we are not justified by works, but by faith. Some of the workers grumbled about the wages they received, but the landowner replied, "Take what is yours and go your way. I wish to give to this last man the same as to you. Is it not lawful for me to do what I wish with my own things? Or is your eye evil because I am good?" (Mt 20:14-15).
Instead of comparing ourselves to others and wondering whether we are first or last, we should ask ourselves whether we are being diligent laborers and working wholeheartedly. Each church member is blessed with different talents, so there is no basis for comparison. From the parable, we see that the amount of time we work is not up to us to determine, but to God. What we can control is how we work. Whenever we have the opportunity to serve God, we should do so diligently, without complaining, for God looks at the heart.