From Reformation Theology: The Christ Honoring Nature of Particular Redemption:
The scope of Christ’s work of redemption is both universal and particular: universal because it includes people of every ethnicity and nation; particular because Christ redeems a people for Himself from out of these nations, having had an eye for a remnant of mankind from every tribe. Here is the climax of God’s redemptive purpose, fulfilling God’s covenant to Abraham to bless the children of promise through his seed (Gen 12:2; Rom 9:6-13). This is why God has commanded the church to preach the gospel to the ends of the earth (Matt 28:18, 19) that He might gather those he has set apart for Himself in every city and town (Acts 18:10; John 17:9, 20).
HT: Monergism