“…when He comes, in that Day, to be glorified in His saints and to be admired among all those who believe, because our testimony among you was believed“
Verse 9 declared that Jesus’ power will be put on display by His presence.
when He comes,
The time when Jesus will recompense believers will be at His Second Coming. The word “when” is indefinite, for we do not know the exact time of this coming.
in that Day,
This coming of the Lord Jesus is the Second Coming, not the Rapture. At this coming, He will fight the battle of Armageddon and then establish His Kingdom on earth for 1000 years (Revelation 19:11-20:4). He will establish justice for the saints then.
to be glorified in His saints
Jesus will be glorified in, not by, the saints. The saints will mirror Jesus on that day. When Jesus comes, He will be the object of great honor because He transformed the lives of His saints. Worldwide glory for Christ is the ultimate purpose of creation. He will rule for 1000 years, and then He will deliver up the Kingdom to the Father so that God may be all in all (1 Corinthians 15:24). He will establish permanent glory for the Father. God’s purpose for our lives is to glorify Christ.
“The glory of the LORD shall be revealed,
And all flesh shall see it together;
For the mouth of the LORD has spoken” (Isaiah 40:5)
and to be admired among all those who believe,
Jesus will be honored in the saints and “admired” by all those who believe. The word “admired” signifies to wonder at, marvel. They will be astonished at who He truly is and that He made good on all His promises. Believers will marvel at His Kingdom.
because our testimony among you was believed
The Thessalonians will participate in the glory of the Second Coming because they believed the gospel. We will not share in this because of our morality but because of the work of Christ on the cross. Christians have a marvelous future because we believed in the gospel.
Jesus is the celebrity for the Christian.
The white heat of God’s presence will blow away pretense. No superficiality will stand in God’s presence. When Jesus comes, we will see the wonder of what He did very clearly. He accrued all of the merit we need for eternity. We could do nothing to gain or earn salvation. He sustains us on earth so that He will receive the glory for that as well. He will overcome the problems of the world by setting up His Kingdom. We will greatly admire His wonderful person and work!