Verlyn Verbrugge (Chapter 7 Genitive and Dative,Basic of Biblical Greek, William D Mounce) writes:
Peace on earth, good will toward men” (Luke 2:14, KJV). You have probably all received Christmas cards containing this part of the angels’ song to the shepherds on the fields of Bethlehem. But most modern translations read differently: “on earth peace to men on whom his [God’s] favor rests” (NIV); “and on earth peace among those whom he [God] favors” (NRSV). The difference between the KJV and the others is the difference between the nominative and the genitive.
The Greek manuscripts used to translate the KJV contain eudokia (nominative), whereas the older manuscripts used to translate the modern versions contain eudokias (genitive) – literally translated, “of good will” or “characterized by [God’s] good pleasure.” In other words, the peace that the angels sang that belonged to the earth as a result of the birth of Christ is not a generic, worldwide peace for all humankind, but a peace limited to those who obtain favor with God by believing in his Son Jesus (see Romans 5:1). What a difference a single letter can make of the text!
Mankind sinned against God, and therefore all people are against God. Only those who are reconciled to God the Father by following God the Son have peace.
But, for those who follow Christ, many times there’s not much peace. Why is that? There are 2 aspects to peace – a “now” peace, and a “not yet” peace. This is called “already, but not yet.” This idea shows up throughout Scripture, and in every day life. We are saved now, but there’s full salvation yet to come. A baseball game is finalized when the bases are loaded and the last home run is hit, but the runners still have to make it around. We have faith now, but our faith grows. We have a garden planted, but it’s not really useful yet because the seeds haven’t matured. So it is with peace.
Peace for the Christian is now, and it’s also growing. Peace is part of the Fruit of the Spirit – love, joy, peace… (Galatians 5). Peace is like an acorn – it’s an oak, but not yet. We have confident assurance that it will be an oak, but it’s not there yet. We have peace, but not real peace. As we abide (give Scripture), it grows – the Spirit makes it grow (John 15:5-7).
Remember the Scripture, “He who began a good work in you will carry it on to completion” (Philippians 1:6) ? We have His promise that we just need to follow and to abide, and He will do the work. We have the seed of peace, but we need to persevere to attain the full fruit of peace. We have it already, but not yet.