Summary: God calls us to live a life of purpose and peace by being set apart to be used by Him in this life as we progress toward Christ-likeness.
"It is God’s will that you should be sanctified." - 1 Thessalonians 4:3a (NIV)
In the Bible, to sanctify something means to set it apart for special use by God. Likewise, to sanctify a person means the same thing - to make them set apart for special use by God. The fact is that God has a plan for each of our lives. We have been saved to serve God's purpose.
The secret to our seeing God's purpose for our lives fulfilled is our willingness to be sanctified, set apart for His use. The process of sanctification has to do with our becoming more and more like Jesus in our daily lives, as Paul makes clear in our text. (READ TEXT)
There are two thoughts that Paul shares with us about how God's grace works in our lives to make us more like Jesus, and thus set apart to be used for His purpose.
1. Being like Christ is our eternal destiny - vs. 29-30
From the beginning, God's plan has been to make us like Jesus. This is our destiny. God announced this intention at creation.
"Then God said, 'Let us make mankind in our image, in our likeness.'" - Genesis 1:26a (NIV)
In all of creation, only human beings, are made "in God's image." This is a great privilege and gives us dignity. Being made in God's image means that man is a spiritual being. Like God, man thinks, feels, and chooses. When man was walking with God before the entrance of sin into this world, he was spiritually alive, and instructed by God as to how to think clearly, feel appropriately, and choose correctly. But with the entrance of sin into this world, the image of God in man became corrupted. Man became spiritually dead, which meant that without God's guidance in his life, his thoughts became inappropriate, as did his feelings and choices. The image of God in man was corrupted.
Which is why God came to rescue us in Christ. He came on a mission to restore the full image we have lost. What does the full "image and likeness" of God look like? It looks like Jesus Christ! The Bible says Jesus is "the image of God" (2 Corinthians 4:4); "the visible image of the invisible God" (Colossians 1:15); & "the exact representation of his being"(Hebrews 1:3). Paul says being like Jesus is the eternal destiny of everyone who has placed their faith in Christ.
When we are saved by the grace of God, we are brought to spiritual life and God begins the work of making us like Jesus in our spirit. And that work of making us like Jesus will be completed the day Christ returns, when we will receive our glorified, resurrection body. Before that, every believer who dies, upon entering the Lord's presence, is made to be like Christ in our thinking, our affections and our choices.
"Dear friends, now we are children of God, and what we will be has not yet been made known. But we know that when Christ appears, we shall be like him, for we shall see him as he is." - 1 John 3:2 (NIV)
Everyone in heaven thinks, loves, and chooses like Jesus. They are like Jesus intellectually, emotionally, and volitionally. Now they're waiting for the day of His return, when they'll receive a resurrection body and will be like Jesus physically. Christ is the first to receive a glorified, resurrection body. That's why Paul says He's "the firstborn among many brothers" (v. 29). When Jesus returns and eternity is ushered in, every believer will be like Him in their spirit, soul, and body.