John Chrysostom

"For God appointed us not unto wrath, but unto the obtaining of salvation through our Lord Jesus Christ, who died for us." Thus God has not inclined to this, that He might destroy us, but that He might save us. And whence is it manifest that this is His will? He has given His own Son for us. So does He desire that we should be saved, that He has given His Son, and not merely given, but given Him to death. From these considerations hope is produced. …

Homily on 1 Thessalonians 9 ↗

Theophylact of Ohrid

Therefore, he says, one must acquire this armor, because God has not appointed us to wrath, that is, He has not destined us to bear His wrath, but rather to acquire us for Himself and save us, having given His Son to death for us. So then, we ought to expect everything beneficial and great amid dangers. For if we believe that He did not spare His own Son for our sake, then let us hope that He will all the more readily deliver us from these dangers. Let us therefore keep this example before us and love both Him and our neighbors. …

Commentary on 1 Thessalonians ↗

Thomas Aquinas

Then when he says, for God has not destined us for wrath, he shows the manner in which God works in us; this is first shown to be out of divine preordination and then as derived from the grace of Christ. Finally, Paul treats the manner in which salvation is to be achieved. He begins with the words, God has not destined us, that is, God has not appointed us: "I appointed you that you should go and bear fruit" (Jn. 15:16); for wrath, that is, that we should deserve His wrath: "God did not make death" (Wis. 1:13). …

Commentary on 1 Thessalonians ↗