1 Thessalonians 2:12-13: “. . . so that you may walk in a manner worthy of the God who calls you into His own kingdom and glory. And for this reason we also constantly thank God that when you received from us the word of God’s message, you accepted it not as the word of men, but for what it really is, the word of God, which also performs its work in you who believe.”
Here, the promise of our eternal inheritance in the kingdom of God is to motivate us to a change of behavior which is the result of the powerful working of God in our lives as believers. When verse 13 mentions “the word of God, which also performs its work in you,” the similarity to 1 Corinthians 4:20 is striking. The difference between Paul’s preaching with power and the mere “words” of the false teachers with whom the Corinthians were enamored is the ability of the “word of the cross” (Paul’s message) to change lives. 1 Corinthians 4:20 says nothing about signs and wonders. - Bob Dewaay; Critical Issues Commentary