Paul loved the believers in Thessalonica; he couldn't return to visit them, so he wrote this letter. He has exhorted and encouraged them; now he 'farewells' them with a prayer, a few final thoughts, ending with a reminder for them to never lose sight of God's grace.
Do not be afraid or discouraged. The battle is not yours, but God's. 2 Chronicles 20:15 The story of Jehoshaphat's lesson for us.
Grace is at the heart of Christianity, yet too often it is missing from our Christian experience. Satan misrepresents and cheapens grace, and many believers have lost hold of it. But if you make a decision to choose grace, your life will be a shining witness for Christ.